I think we should change it to "jpa" and only support the implementation we feel is the best. If folks want to document how to change from one implementation to another, that's cool. If we find
that OpenJPA is better than Hibernate JPA, we can switch. This is similar to what we've done with JSF - we call it the generic name and that allows us to switch implementations if we ever need to w/o messing up anything too bad. It's been fairly easy to switch between MyFaces and Sun's RI - I imagine the same thing is (or will be) possible with JPA. In other words, no code will change, just dependencies and end-users should be able to change that easily enough.

More discussion at http://www.nabble.com/jpa-hibernate-vs.-jpa-tf4370346s2369.html.