If you've been trying to find GssUtil.exe so you can script the new Beta 3 release of TFS, you won't be able to!  Instead, you'll use the new TfsSecurity.  Luckily, adding groups and individual users uses the same command line (except of course, the name of the EXE), so it's a simple search and replace!  So, in short, there's been a name change, GssUtil.exe is now TfsSecurity.exe (at least for the purposes of roles and logins).

Happy TFSing!