I've posted the slides for two recent presentations.
The first is one I did for this year's TSS symposium. It discusses some of the issues surrounding persistent identity, and how they affect everything from how you define equals() for a persistent object, to what kind of cache architecture makes sense.
The next is a presentation about EJB3, focussing on entity beans. (Note that, so far, almost all of the blog coverage of EJB3 was written by people who havn't actually read the spec - the draft is not available just yet.)
Finally, I am hosting a BOF at JavaOne, on Monday at Monday 10:30 PM, at the North Meeting Room. I'll be talking about how ORM solutions work with /graphs/ of objects, especially in the context of detach/reattach. I'll compare three different approaches: peristence by reachability, Hibernate, and EJB3.