This screencast shows how to develop and deploy your first JRuby app
using NetBeans Ruby IDE and deploy it on GlassFish. Enjoy it at:

http://blogs.sun.com/arungupta/entry/screencast_web6_first_jruby_app

This screencast shows how NetBeans IDE provides a complete IDE for
Rails. It uses the goldspike plugin to generate a standard WAR file
and then deploys the WAR file to GlassFish.

And if you prefer command-line tools, then here is another entry
showing how GlassFish V3 can deploy Rails app natively without any
plugins:

http://blogs.sun.com/arungupta/entry/first_jruby_on_rails_app

Thanks,
-Arun