Our dear friend Etienne has written up his experiences installing TFS 2008 on Windows 2008.  It's definitely more complex than installing it on Windows 2003.  The issues revolve around our uncertainty of the status of WSS on Windows 2008 at the time we were shipping TFS 2008.  Etienne's blog post details the steps he went through to get it installed and working.  Learning from what he has done can save you time and trouble until we get a chance to simplify the experience.

The thing Etienne didn't cover, that I expect many customers will face, is upgrading a Windows 2003 server with TFS on it to Windows 2008.  Unfortunately, this will be even trickier.  The stumbling blocks include...  You will have to upgrade TFS 2005 (if that's what you have) to TFS 2008 because TFS 2005 doesn't support Windows 2008.  You can't upgrade the OS and have TFS keep working.  At best you can upgrade to OS and reinstall TFS in some series of steps.  At worst, you will need to back everything up, flatten the box and reinstall the OS, restore the TFS databases and then reinstall TFS.  I will make sure we have some good instructions for all of this and then point you at them.

Brian