Brian Harry's posted the final feature list for TFS 2008 (f.k.a "Orcas"):  http://blogs.msdn.com/bharry/archive/2007/08/08/final-tfs-2008-feature-list.aspx

A few of my favorites:

  • SharePoint 2007 support
  • SQL 2008 support
  • Simpler installation
  • Native CI support
  • NET object model for the build server
  • Incremental builds & gets
  • Get latest on checkout