Most of the time, source control in Visual Studio Team System is pretty straight forward. But then, somebody leaves the project and left with some files still checked out. If you want to perform an "undo pending changes" from another user's workspace, you have to open the Visual Studio Command Prompt and use the Team Foundation commandline tool TF.exe like this:

TF.exe undo /workspace:<WorkspaceName>;<UserName> $/<TeamProject>/<FileLocation> /s:http://<YourTFSServer>:8080

TF.exe is also handy if you want to get the list of all the files that are still checked out by another user:

TF.exe status $/<TeamProject> /user:* /recursive /login:<YourDomain>\<YourUserName>,<YourPassword>

By David Stroobants, .Net Solutions Architect