If recently worked with several developers that were unable to open the Team Explorer 2008 window (or if they did open it, the window was blank). They had pre-release versions of Visual Studio 2008 installed and despite following the instructions on uninstalling previous versions, were unsucessful. Having found the fix for this issue, I thought I'd share it in case anyone else encounters it.
Open a Visual Studio 2008 command prompt and run the following command:
It will take awhile for this command to complete, but afterwards, the issue should be resolved. Here is documentation on the /setup switch if you would like to know more about it.