We were having similar problems with PermGen unrelated to remote calls, we upgraded to Javassist 3.4 and Hibernate 3.2.1.GA off of HEAD, and it looks to have greatly improved the problem. Might be worth trying for you as well.
We are already using Javassist 3.4 but Hibernate in Version 3.2.0.GA.
I will check the newer Hibernate Version.
The newer hibernate version didn't solve the problem.
I'll post the problem to the MyFaces forum, too.
I can't imagine that no MyFaces user has the same problem ???
This may or not be related. But I recently found that using Tomahawk tags (dataList, dataTable) in my Seam/EJB3 was causing serious PermGen memory leak problems. I replaced both with other MyFaces and Seam components and my problem went away. Granted, the Seam documentation now recommends against using Tomahawk tags, so consider this a re-affirmation.