Our development environment is based on a self-contained JRuby (1.0.3) on Rails (1.2.6) application stored in a Mercurial repository. The IDE we use is NetBeans 6 with Ruby support and Mercurial plugin. The DB of our choice is MySQL and servers we use during development are WEBrick and Glassfish v2ur1.
As for production environment they use “a pair of load-balanced T2000 with Solaris 10, JDK6 and SJSAS 9.1u1. These two servers share a nfs NAS drive used for file storage and fragment cache storage. The DB backend is a MySQL database server, which we access through a connection pool set up in the app server.”
They comment that most C-based ruby gems are not compatible with JRuby but the support is improving with the work of jruby-extras project. They used Java for SOAP-over-HTTPS based authentication webservice and for long-running processes by using a servlet filter.
JRuby is starting to enter the enterprise space, dominated by Java. Sun is investing much in Ruby by supporting the JRuby project, JRuby in Glassfish and NetBeans Ruby support. I think the number of JRuby-powered applications will increase this year and Ruby be considered a serious language.