Of just the four that you list, only JBoss has an EJB 3.0 implementation in production. The others are working on it, and I believe I saw in the authors other posts, that Oracle's App Server is in Beta. I am not sure how close the other two are.
But the other production app servers out there that support EJB 3.0 is Sun's GlassFish, JBoss, and one other that I can't remember the name.
JBoss' server is not certified EJB 3.0 yet. SUn's and the other is certified EJB 3.0
Originally posted by Bruce Jin: Thanks for the info. It looks like it is a little early to dig into EJB 3.0 right now since most containers don't support it yet.
It's alright to learn that since now, if your purpose is just to learn the EJB 3.0 itself, not the container-specific features that support EJB 3.0. Sun's Glassfish, which is the reference implementation of EJB 3.0 spec, is already available for us to play around with the new and cool features of EJB 3.0. It shouldn't be a problem to deploy your EJB code in other upcoming EJB 3-compliant containers later, as long as you don't use any container-specific features.
Just my 2 cents...
Co-author of SCMAD Exam Guide, Author of JMADPlus SCJP1.2, CCNA, SCWCD1.4, SCBCD1.3, SCMAD1.0, SCJA1.0, SCJP6.0