I'm in the airport, but I wanted to add to the blogs reporting that JRuby 1.0.1 and Jython 2.2 have been released.
JRuby 1.0.1 is basically just a maintenance release to 1.0. It includes various compatibility fixes that have filtered in since the release, and doesn't do much to improve performance. JRuby 1.1 will come out by November, and should have all the latest research and perf work, including a complete compiler to JVM bytecode.
Jython 2.2 is much bigger news. After years of sleepily crawling along, the 2.2 release of Jython has finally been released. With 2.2 behind them, the Jython team can now be more ambitious about adding Python 2.3, 2.4, and 2.5 features. Much of that work has already started. Also coming up is a new JVM bytecode compiler. If you're a Python guy, give Jython a try today...those guys have put a lot of time and effort in.
I also understand that Groovy is supposed to have their 1.1 release out some time in October. Happy times for dynlangs on the JVM!