While deploying hibernate as a Resource Adapter (to WebLogic), I found myself wishing that I had two separate hibernate jars-- one containing the hibernate interfaces that application components interact with, and one containing the implementation. I believe that such a separation would allow for a cleaner deployment. (My current deployment has all of hibernate on the application server class path. I think an alternative would have been to deploy hibernate with each application.)
My hope was that by having two jars, I could put the interfaces on the application server class path, and deploy everything else (including the 3rd party jars) in a single .rar.

When I tried to re-package things for myself (starting the interfaces at net.sf.hibernate.Session), I quickly became hopelessly entangled by dependencies.

I'm curious if anyone has any thoughts (does this seems worthwhile, is the deployment I'm suggesting valid or is there a problem with my thinking, is repackaging easy for someone more in-the-know or extraordinarly hard)?

I can see how that would be highly worth-while. Its exactly the ideal when dealing with ejbs, implementation details inside the ear file and interfaces and common components in seperate jars.

One issue here would be (as I think you are saying you ran into) would be that a lot of the third party jars which hibernate uses would need to also be available to the clients of the connector. But I have not attempted this yet, and so cannot give you any advice really.

If you do figure something out, please post back here (or better yet on the wiki) as this will be extremely valuable to others attempting this.

As you state, my goal is to make the rar deployment similar to an EJB deployment. From brief experimentation with another rar on weblogic 8.1, the interaction between an application component and that connecter seems quite similar to the interaction between a web app and an EJB in an EAR.

The problem I ran into wasn't actually due to 3rd party jars. (My guess is they will be fine hidden in the rar).

I actually ran into a problem because my interface to the connector required SessionFactory and Session, which requires Type.
Unfortunately, Type pulled in a lot of other stuff.

I think it will take someone with serious hibernate expertise to figure out the best way to pull this stuff apart. If people think it is worthwhile though, I'm happy to add it to JIRA.

I will try to contribute a WIKI in a short while about what I learned deploying as a rar.