I'd applied the SP1 to an installed RTM version and when I try to access to the team server, an error indicating bad TFS_SCHEMA_VERSION occurs:
The requested schema property TFS_SCHEMA_VERSION did not match the expected value. The server requires the Microsoft Team Foundation Server 2010 (SP1) schema but the database currently implements Microsoft Team Foundation Server 2010 (RTM).
I've found a trick that seems to work, I just change the advanced properties of the Default collections database.
To to that:
It works fine for me...