I found the following points noteworthy:
- JRuby 1.1.x is out
- JRuby continues to significantly outperform CRuby. At least in certain benchmarks. This hasn't quite been my experience comparing the same Rails app deployed in Glassfish vs. running through Mongrel, but... I should probably check again, ensuring system resources aren't to blame.
- Ruby code is now fully byte compiled either just-in-time, or you can pre-compile your ruby scripts into Java .class files ahead of time (using jrubyc)!
- Warbler is an easy way to make .war files out of your Rails app, for deployment into any Java web app container. As Charles says, hand them to your ops team, and no one might ever know your code was written in Ruby!
- A handy gem called glassfish_rails is out that makes firing up glassfish using your Rails app a snap. I believe this is only for Glassfish v3, which is a technology preview release. One thing I want to see on this is if you can make changes to your Ruby code and have this reflected immediately (without restarting Glassfish). I really hope so.