cross-VM development

Russell talks about how JVM needs to grow past Java. Sure, that would be nice.

But, one of the things I love about CLR is the tools I get to use when coding against it. One thing I love about VJM is that it remains single most solid cross-platform runtime for managed code (I don't yet consider Mono solid enough).

Here's a question:
Has anyone tried to build anything using J# on Windows and Sun's JVM on other platforms.
It should be theoretically possible:
J# has the same syntax as Java. J# comes with some kind of converter jbimp.exe .jar to MSIL .dll

I've stumbled on this note while looking for prior art on this, but there's not much more in terms of experience reports.