If you're like me and tend to push the envelope in terms of what you install on your development machine, you probably have installed the GDR update for Visual Studio Team System Database Professionals aka "DataDude".
One thing I learned about this (and it really should be obvious, but for some reason it wasn't) is that even though the installation of Visual Studio Service Pack 1 seems to go fine, realize that the DataDude GDR is actually not updated with this SP. So, in order to get things in true working order (Able to use the RTM features of SQL Server 2008) you'll need to uninstall (not repair) the DataDude GDR release, then install SP1, then reinstall the DataDude GDR.
In my case, I installed SP1, then tried to use the Schema Compare function within DataDude against an RTM SQL 2008 instance. This failed, and after a bit of whining to various people, I learned that the GDR needed to be reinstalled. After learning that the repair function didn't work to solve the problem, I uninstalled the GDR and reinstalled it. This seemed to work, but I don't *really* know what state my environment is in.