First what would be pointed out in other places, a question like
"what are the advantages of EJB3.0 over Hibernate"
Would like what are the advantages of Apples over Green Apples?
Hibernate 3.x is an implementation of EJB3.0 or better an implementation of JPA, so it really isn't an either or, it is a question of which implementation of EJB3.0/JPA that you want to use. Use Hibernate is a superset of JPA, meaning that there are some add-ons to Hibernate that has some more features than what is in the spec, but if you program to the JPA spec with Hibernate you have JPA.
Mark