I am using an entitylistener with a prepersist annotation. This entity listener needs to get the primary key of the entity being inserted. The EJB3 spec indicates that generated primary keys are available in the postpersist lifecycle but mentions nothing about the key being available in the prepersist phase.

Hibernate is generating the key before calling my entity listener's prepersist method. Is this hibernate specific? Is it safe to rely on this current behavior?

it is not safe, not even in Hibernate :-)