Hi,
The latest checkout has a problem with even the most trivial example of \startalign (taken from the wiki):
\starttext
\startformula \startalign
 \NC v \NC = u + at \NR
 \NC h \NC= ut + \frac12 gt^2 \NR
\stopalign \stopformula
\stoptext


% context --version

mtx-context     | ConTeXt Process Management 0.60
mtx-context     |
mtx-context     | main context file: /opt/context-minimals/texmf-context/tex/context/base/context.mkiv
mtx-context     | current version: 2012.07.04 15:55

Output
*****
*****     ConTeXt-IV output:
*****     cd "/home/3shared/Source/prash/doc/context-trials"
*****     context --nonstopmode demo.context
*****

mtx-context     | run 1: luatex --fmt="/home/prash/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/cont-en" --interaction="nonstopmode" --jobname="demo" --lua="/home/prash/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e/formats/cont-en.lui" --no-parse-first-line --c:currentrun=1 --c:input="./demo.context" --c:kindofrun=1 --c:nonstopmode "cont-yes.mkiv"
This is LuaTeX, Version beta-0.70.2-2012052410 (TeX Live 2012)
 \write18 enabled.
(/opt/context-minimals/texmf-context/tex/context/base/cont-yes.mkiv

ConTeXt  ver: 2012.07.04 15:55 MKIV  fmt: 2012.7.4  int: english/english

system          > cont-new.mkiv loaded
(/opt/context-minimals/texmf-context/tex/context/base/cont-new.mkiv
system          > beware: some patches loaded from cont-new.mkiv
)
fonts           > latin modern fonts are not preloaded
languages       > language en is active
(demo.context{/opt/context-minimals/texmf-fonts/fonts/map/pdftex/context/mkiv-base.map}
fonts           > preloading latin modern fonts (second stage)
fonts           > typescripts > unknown: library 'loc'
{/opt/context-minimals/texmf-fonts/fonts/map/dvips/lm/lm-math.map}{/opt/context-minimals/texmf-fonts/fonts/map/dvips/lm/lm-rm.map}
fonts           > virtual math > unable to resolve name mapsfromchar
fonts           > fallback modern rm 12pt is loaded
! Use of \expandafter doesn't match its definition.

system          > tex > error on line 4 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4 >>   \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    


\math_both_eqalign_no_aligned ...andafter \bgroup
                                                  \the \scratchtoks \crcr
<to be read again>
                   \NC
l.4  \NC
         v \NC = u + at \NR
! Missing { inserted.

system          > tex > error on line 4 in file demo.context: Missing { inserted ...

1     \starttext
2    
3     \startformula \startalign
4 >>   \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<to be read again>
                   \crcr
<to be read again>
                   \NC
l.4  \NC
         v \NC = u + at \NR
! Missing # inserted in alignment preamble.

system          > tex > error on line 4 in file demo.context: Missing # inserted in alignment preamble ...

1     \starttext
2    
3     \startformula \startalign
4 >>   \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<to be read again>
                   \crcr
<to be read again>
                   \NC
l.4  \NC
         v \NC = u + at \NR
! Extra alignment tab has been changed to \cr.

system          > tex > error on line 4 in file demo.context: Extra alignment tab has been changed to \cr ...

1     \starttext
2    
3     \startformula \startalign
4 >>   \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<template> \endtemplate
                       
\math_alignment_NC ->\aligntab
                              
l.4  \NC v \NC
               = u + at \NR
! Extra alignment tab has been changed to \cr.

system          > tex > error on line 4 in file demo.context: Extra alignment tab has been changed to \cr ...

1     \starttext
2    
3     \startformula \startalign
4 >>   \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<template> \endtemplate
                       
\NR ->\aligntab
                \dostoptagged \dodoubleempty \math_alignment_NR_indeed
l.4  \NC v \NC = u + at \NR
                          
! Use of \expandafter doesn't match its definition.

system          > tex > error on line 5 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5 >>   \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    


\syst_helpers_inspect_next_optional_character ...
                                                  \fi
<to be read again>
                   \NC
l.5  \NC
         h \NC= ut + \frac12 gt^2 \NR
! Extra alignment tab has been changed to \cr.

system          > tex > error on line 5 in file demo.context: Extra alignment tab has been changed to \cr ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5 >>   \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<template> \endtemplate
                       
\math_alignment_NC ->\aligntab
                              
l.5  \NC
         h \NC= ut + \frac12 gt^2 \NR
! Extra alignment tab has been changed to \cr.

system          > tex > error on line 5 in file demo.context: Extra alignment tab has been changed to \cr ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5 >>   \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<template> \endtemplate
                       
\math_alignment_NC ->\aligntab
                              
l.5  \NC h \NC
              = ut + \frac12 gt^2 \NR
! Use of \expandafter doesn't match its definition.

system          > tex > error on line 5 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5 >>   \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    


\frac ...acmode \expandafter \math_fractions_auto
                                                  \or \expandafter \math_fra...
l.5  \NC h \NC= ut + \frac
                          12 gt^2 \NR
! Extra alignment tab has been changed to \cr.

system          > tex > error on line 5 in file demo.context: Extra alignment tab has been changed to \cr ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5 >>   \NC h \NC= ut + \frac12 gt^2 \NR
6     \stopalign \stopformula
7    
8     \stoptext
9    

<template> \endtemplate
                       
\NR ->\aligntab
                \dostoptagged \dodoubleempty \math_alignment_NR_indeed
l.5  \NC h \NC= ut + \frac12 gt^2 \NR
                                    
! Use of \expandafter doesn't match its definition.

system          > tex > error on line 6 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    


\syst_helpers_inspect_next_optional_character ...
                                                  \fi
<to be read again>
                   \stopalign
l.6 \stopalign
               \stopformula
! Use of \expandafter doesn't match its definition.

system          > tex > error on line 6 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    


\formulaparameter ...er \doformulaparentparameter
                                                  \csname \??formula \curren...
\stopinnermath ...stop \formulaparameter \c!align
                                                  \endcsname
\stopdisplaymath ->\stopinnermath
                                  $$\par \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
! Missing \endcsname inserted.

system          > tex > error on line 6 in file demo.context: Missing \endcsname inserted ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    

<to be read again>
                   \422>:parent
\formulaparameter ...ormula :\s!parent \endcsname
                                                  {#1}\fi \endcsname
\stopinnermath ...stop \formulaparameter \c!align
                                                  \endcsname
\stopdisplaymath ->\stopinnermath
                                  $$\par \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
! Use of \csname\endcsname doesn't match its definition.

system          > tex > error on line 6 in file demo.context: Use of  ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    

<recently read> \422>:parent
                            
\formulaparameter ...ormula :\s!parent \endcsname
                                                  {#1}\fi \endcsname
\stopinnermath ...stop \formulaparameter \c!align
                                                  \endcsname
\stopdisplaymath ->\stopinnermath
                                  $$\par \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
! Display math should end with \Ustopdisplaymath.

system          > tex > error on line 6 in file demo.context: Display math should end with \Ustopdisplaymath ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    


\stopinnermath ...laparameter \c!align \endcsname
                                                 
\stopdisplaymath ->\stopinnermath
                                  $$\par \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
! Missing $ inserted.

system          > tex > error on line 6 in file demo.context: Missing $ inserted ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    

<inserted text>
                $
<to be read again>
                   \normalpar
\stopdisplaymath ->\stopinnermath $$\par
                                         \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
! Display math should end with $$.

system          > tex > error on line 6 in file demo.context: Display math should end with $$ ...

1     \starttext
2    
3     \startformula \startalign
4      \NC v \NC = u + at \NR
5      \NC h \NC= ut + \frac12 gt^2 \NR
6 >>  \stopalign \stopformula
7    
8     \stoptext
9    

<to be read again>
                   \normalpar
\stopdisplaymath ->\stopinnermath $$\par
                                         \afterdisplayspace \par \egroup
\strc_formulas_stop_formula ...native \v!formula }
                                                  \dostoptagged \dostoptagge...
l.6 \stopalign \stopformula
                          
backend         > xmp > using file '/opt/context-minimals/texmf-context/tex/context/base/lpdf-pdx.xml'
pages           > flushing realpage 1, userpage 1
) )</opt/context-minimals/texmf-fonts/fonts/opentype/public/lm/lmroman12-regular.otf> mkiv lua stats > used config file - selfautoparent:/texmf/web2c/texmfcnf.lua
mkiv lua stats  &gt; used cache path           - /home/prash/texmf-cache/luatex-cache/context/5fe67e0bfe781ce0dde776fb1556f32e
mkiv lua stats  &gt; resource resolver         - loadtime 0.015 seconds, 0 scans with scantime 0.000 seconds, 0 shared scans, 45 found files, scanned paths:
mkiv lua stats  &gt; stored bytecode data      - 306 modules, 65 tables, 371 chunks
mkiv lua stats  &gt; cleaned up reserved nodes - 41 nodes, 9 lists of 435
mkiv lua stats  &gt; node memory usage         - 2 glue, 2 penalty, 9 attribute, 30 glue_spec, 3 attribute_list
mkiv lua stats  &gt; node list callback tasks  - 6 unique task lists, 5 instances (re)created, 145 calls
mkiv lua stats  &gt; used backend              - pdf (backend for directly generating pdf output)
mkiv lua stats  &gt; loaded patterns           - en::2
mkiv lua stats  &gt; jobdata time              - 0.000 seconds saving, 0.001 seconds loading
mkiv lua stats  &gt; callbacks                 - 290 direct, 568 indirect, 858 total
mkiv lua stats  &gt; randomizer                - resumed with value 0.81745024575733
mkiv lua stats  &gt; lxml preparation time     - 0.000 seconds, 0 nodes, 15 lpath calls, 0 cached calls
mkiv lua stats  &gt; result saved in file      - demo.pdf
mkiv lua stats  &gt; loaded fonts              - 33 files: stmary10.afm lmmono12-regular.otf lmmono8-regular.otf lmmono9-regular.otf lmroman12-bold.otf lmroman12-regular.otf lmroman7-bold.otf lmroman7-regular.otf lmroman9-bold.otf lmroman9-regular.otf lmsans12-regular.otf lmsans8-regular.otf lmsans9-regular.otf eufb10.tfm eufb7.tfm eufm10.tfm eufm7.tfm msam10.tfm msam7.tfm msbm10.tfm msbm7.tfm lmex10.tfm lmmi12.tfm lmmi7.tfm lmmi9.tfm lmmib10.tfm lmmib7.tfm lmsy10.tfm lmsy7.tfm lmsy9.tfm rm-lmr12.tfm rm-lmr7.tfm rm-lmr9.tfm
mkiv lua stats  &gt; fonts load time           - 0.240 seconds
mkiv lua stats  &gt; luatex banner             - this is luatex, version beta-0.70.2-2012052410 (tex live 2012)
mkiv lua stats  &gt; control sequences         - 34579 of 65536 + 100000
mkiv lua stats  &gt; current memory usage      - 46 MB (ctx: 47 MB)
mkiv lua stats  &gt; runtime                   - 0.645 seconds, 1 processed pages, 1 shipped pages, 1.550 pages/second