Looks ok here with last mkiv stable and luatex beta-0.42.0-2009071723
If you have a mkiv beta, maybe you need last luatex trunk from svn .


# context --version && luatex --credits
MTXrun | main context file: /opt/luatex/luatex-lunatic/minimals-git/tex/texmf-context/tex/context/base/context.tex
MTXrun | current version: 2009.07.17 17:23

This is LuaTeX, Version beta-0.42.0-2009071723

The LuaTeX team is Hans Hagen, Hartmut Henkel, Taco Hoekwater.
LuaTeX merges and builds upon (parts of) the code from these projects:

tex       by Donald Knuth
etex      by Peter Breitenlohner, Phil Taylor and friends
omega     by John Plaice and Yannis Haralambous
aleph     by Giuseppe Bilotta
pdftex    by Han The Thanh and friends
kpathsea  by Karl Berry, Olaf Weber and others
lua       by Roberto Ierusalimschy, Waldemar Celes,
             Luiz Henrique de Figueiredo
metapost  by John Hobby, Taco Hoekwater and friends.
xpdf      by Derek Noonburg (partial)
fontforge by George Williams (partial)

Some extensions to lua and additional lua libraries are used, as well as
libraries for graphic inclusion. More details can be found in the source.
Code development was sponsored by a grant from Colorado State University
via the 'oriental tex' project, the TeX User Groups, and donations.

Compiled with libpng 1.2.38; using libpng 1.2.38
Compiled with zlib 1.2.3; using zlib 1.2.3
Compiled with xpdf version 3.02pl3