Trying to use roman numerals as pagenumbers failed. What am I doing wrong or has some other thing changed? 

A minimal example follows. Changing romannumerals into characters doesn't make a difference.
This is ConTeXt  ver: 2012.01.09 10:08 MKIV 

% test pagenumber conversion
\setuppapersize[A6][A6]
\starttext
\setuppagenumber[number=1]
\setuppagenumbering[conversion=romannumerals] % or: characters
page 1\page
page 2\page
page 3\page
\setuppagenumber[number=1]
\setuppagenumbering[conversion=numbers]
page 4\page
page 5\page
page 6\page
\stoptext

Hans van der Meer