Still being discussed - not decided yet - but it looks like we have an interesting proposal on the mailing list about the future for the hibernate forums.
Put the forum into a read only mode
Add a banner explaining the move to Stackoverflow (similar in content to what's in the post
Create a Hibernate Team on Stackoverflow
Make sure all Hibernate related tags and wiki pages are up to date
Add a "Where-to-post summary" to hibernate.org
Create a hibernate-discussions mailing list!?
Update instructions on http://hibernate.org/community/