So I've been looking around, and I see that we have a Java runtime that works, but I have no idea how good it is or any of the specifics. Can any one tell me how this runtime is, and would it be practical to develop GP2X applications in java?

well... there is a few games and demos on the archive i believe. Some things run quite well with the java runtime we've got, they are still developing though. I am not quite sure what is missing, since I do not have the appropriate knowledge about java, but it seems to be some major part that is still not included.

So, it is functional, but not a fully fledged runtime environment. maybe there is more about this on the wiki...