Many thanks for the reply Hans. I'm a little puzzled by what happens when I use \setuppagenumbering[alternative=doublesided]. For example:
\showframe
\setuppapersize[letter][letter]
\setuppagenumbering[alternative=doublesided]
\setuplayout[
grid=no, % grids make a mess of complex float placement
topspace=0.50in, % the space at the very top of the page
backspace=1.75in, % the space for binding gutter
header=0.40in, % the space for headers
footer=0.40in, % the space for footers
leftmargin=0.75in, % the space for margin notes
rightmargin=1.00in, % the space for margin notes
height=fit,
width=5.25in]
\starttext
test
\startspread
\placefigure
[page]
[Fig:a]
{Figure a caption goes here}
{\externalfigure[a][width=0.8\makeupwidth]}
\placefigure
[page]
[Fig:b]
{Figure b caption goes here}
{\externalfigure[b][width=0.8\makeupwidth]}
\stopspread
\stoptext
Cheers,
Randall
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TeXExec 5.4.3 - ConTeXt / PRAGMA ADE 1997-2005
texexec : TeXExec 5.4.3 - ConTeXt / PRAGMA ADE 1997-2005
texutil : TeXUtil 9.0.0 - ConTeXt / PRAGMA ADE 1992-2004
tex : pdfeTeX, 3.141592-1.30.4-2.2 (Web2C 7.5.5
)
context : ver: 2006.02.03 21:03
cont-en : ver: 2006.02.03 21:03 fmt: 2006.2.10 mes: english
cont-nl : ver: 2006.02.03 21:03 fmt: 2006.2.10 mes: dutch
total run time : 7 seconds