2 short weeks after the JRuby team released version 1.1 we'll see the next release some time today. Version 1.1.1 resolves 41 issues and focuses on stability, performance and compatibility according to Charles Nutter.
Issues still exist with JRuby on GCJ and possibly on IBM's JVM 5. Anyone using these platforms is encouraged to submit bugs or possibly fixes.
The pace on this project is truly amazing... I plan to write-up a few posts about a recent project I worked on which used JRuby and Rails to speed development, exciting times my friends!