As ISV, we have put our new Warehouse application into production for more customers using JBoss and MySQL. We started with JBoss 2.2.2 and are now 3.2.1. The system has both Swing and some web clients for status requests using JBoss EJBs (1.1) and Jetty. In production now from more than 2 year and everything is running without problems.
All tested with other J2EE servers, at end JBoss was the best in performance and price.

Ciao.