There seems to be a great deal of fun going on in the Java community over JDO, EJB, and the like. JDO is an OO database influenced spec that's been moving in the direction of handling O/R persitence as well. I always had some issues with the way they approached things, but they were in the realm of legitimate technical differences. But it was always EJB that had the real mindshare, even though technically it was a disaster area. Now it appears that Oracle (i.e. TOPLink) and an open source product called Hibernate with a similar sort of architecture are abandoning efforts to work with JDO and instead have managed to influence the direction of EJB 3.0 towards a much lighter-weight persistence mechanism.
It's all very interesting, looking in from the outside, and there's lots of entertaining name-calling. Most of what I saw was in a thread on theserverside.com, but alas that thread seems to have expired or been purged while I was off sick.
Anyway, I think things will get interesting in that world. I don't know why Oracle and Hibernate chose to go with EJB. I know that there were some tensions with the JDO approach, but tensions doesn't begin to describe the problems with EJB. On the other hand, EJB's persistence has by now failed spectacularly enough that the committee seems willing to admit the previous two approaches were a bad idea and do a complete rewrite listening to someone who knows something. So perhaps they'll come out with something reasonable (but of course, also backward compatible with the previous two). Given my expriences with that group, I'm doubtful. Fortunately, it doesn't really affect me one way or the other.