Since we are comparing O/R tools here, the EJB 3.0 developments shouldn’t be missed either.
EJB 3.0 in a nutshell, An overview and critical analysis of the latest EJB specification by Anil Sharma, offers an excellent survey! Moreover, after reading this article, it also seems that Hibernate and EJB 3.0 have (quite) some similarities.
To me the attribute oriented nature looks a lot like what I’m doing with Xdoclet right now, which I find a convenient way of developing (only focussing on the implementation class).
Summarizing, the EJB 3.0 developments seem to be promising indeed! The only thing I’m afraid of is that it might come a little late. Even worse, it may take quite some time before the major application servers support EJB 3.0.