SPS2007 with TFS - Test it if you dare!
Amazing efforts by Mike Glaser and the VSTS Rangers (MCS consultants) have yielded results: a guide to using WSS 3.0 with TFS. If you're brave enough to try this, please send your feedback to Brian Keller.
Otherwise you can wait for Orcas. Apparently Beta 2 will have SPS2007 integration.