Probably your first port of call is the java.sun.com site.
Its got the EJB 2 specification, APIs etc plus an initial tutorial (
http://java.sun.com/j2ee/tutorial/1_3-fcs/index.html). Also there are design
patterns and best practices.
There are plenty of other sites and newsgroups on the web with stuff just do a search on any search engine.
If you want a book. I've just got the 3rd edition of Enterprise Javabeans by Richard Monson-Haefel as it appeared to be one of the first EJB book with EJB2, haven't read it in depth but first looks appear to give a good introduction\tutorial on EJB2.
Hope that helps
Phil