On behalf of the whole JRuby team, Thomas Enebo has announced the release of JRuby 0.9.8. Hundreds of minor tweaks, fixes, and features have been added, and now Ruby on Rails is officially supported. The team report a 98% pass rate for Rails 1.2.1's own unit tests, and if you've seen how deep the Rails tests go, that's pretty good work. It's pretty clear JRuby isn't too far from a 1.0 release now from which full compatibility should be available.