I saw an internal mail about this today and it seemed like something worth sharing.  Now that Sharepoint is no longer included in Windows Server 2008, you have to install it yourself.  Further, when installing TFS on Windows 2008, the TFS installation process won't automatically install Sharepoint (this is due to the fact that there was a great deal of uncertainty at the time about exactly what was being done with Sharepoint in Windows 2008 and we had to take the safe route of not messing with it).

The issue is this.  If you try to install WSS 3.0 on Windows 2008, it will not install.  It will tell you that you have to install SP1 and you will probably wonder how you can do that without first installing WSS 3.0.  The answer is that you need to install the Windows Sharepoint Services 3.0 with SP1 installer that bundles Sharepoint 3.0 and SP1 together.

Hopefully this will save you a bunch of head scratching...

Brian