Hm, only Subversion so far has good and "easy" GUI integration over all platforms. GIT's only failing on Windows, or Mercurial's on the Mac. For a multi-level of expertise, multi-platform, multi-disciplinary team (front-end, back-end, flash developers) working on Macs, Windows and Linux boxes, it seems to me SVN is still the path of least resistance. Much as I hate it.