Brian Harry, of the TFS team has listed all of the final Team Foundation Server 2008 features on his blog here: http://blogs.msdn.com/bharry/archive/2007/08/08/final-tfs-2008-feature-list.aspx.  I've published the list of new features in Visual Studio Team System 2008 (the client for TFS) in an earlier posting on my blog here: http://robertsheltonjr.spaces.live.com/blog/cns!DCB2904F175F67AA!292.entry

~ Robert Shelton