I actually considered doing just that, for weeks.  As much as I would have <i>loved</i> to do it, the Java application is a desktop app, and putting in JRuby would have added something like 15 MB to the installer.<p>I did propose that to work, though (we do generation on the server so the size doesn't matter), and we have done it if we had an acceptable supply of Ruby-speaking engineers.  Bad news for them, good news for me: I would hate to have their business hobbled when I leave.