All J2EE developers take note: JBoss has released their much-touted JBoss 3.0 which you can download
at the JBoss download page.
This is really something to check out. The entire thing is written around a microkernel and all services are hot-deployable. You can add datasources and MBeans while the thing is running. Really like that.
Last time I checked it I still found a bug with the JMS stuff, but the bug had been solved and was on the CVS tip..