[ Persistence API ] More simplified than ever, but still difficult

I'm learning Persistence API which is a major axis of EJB 3.0 Specification. It decreases complexity of EJB 2.1 spec with annotation ( like @XXXXX ) , which replaces the notion of EntityBean in EJB 2.1.

I googled the articles dealing with java persistence and found something useful.

http://www.ibm.com/developerworks/websphere/techjournal/0502_col_barcia/0502_col_barcia.html
http://www.zdnet.co.kr/builder/dev/java/0,39031622,39153468,00.htm
http://java.sun.com/javaee/5/docs/tutorial/doc/bnbqw.html
http://java.sun.com/developer/technicalArticles/J2EE/jpa/
http://weblogs.java.net/blog/guruwons/archive/2006/06/ejb_30_sessions.html

Because java persistence technology is strongly related with ejb 3.0, I need to expand the coverage of learing from pure persistence to ejb3.0 and j2ee spec, which may result in enomouse amount of reading, coding and endurance. -_-;;

Nothing to be gained with ease....