Check out this:
Over view
It is a project that attempts to be able to cross-compile programs written in a variety of source languages to a variety of target languages. One of the initial test cases was to write programs in Java and run them on an iPhone. Watching the video on the site is worthwhile.
With that said, I haven't tried it. The project seems quite beta, and there isn't a lot of activity on their SourceForge site.
