go to
http://theserverside.com You could register (free) and download Mastering
EJB II for evaluation. This book covers EJB 2.0. Remember Mastering EJB (without II) covers EJB 1.0.
Also Oreilly's Enterprise
Java Beans, 3rd Edition is a very good book but you have to pay for it.
Hope this helps
Chintan