I've just added descriptions and notes to docs.communityserver.org regarding some of the changes in SP3 I was involved with:
All of these changes and many more are available in the preview release of Community Server 2007 SP3.
Read the complete post at http://feeds.getben.com/~r/BenTiedt/~3/149351001/some-notes-about-community-server-2007-sp3.aspx