If you have a computer (or many) computers that blue-screened after installing Windows 7 SP1 via WSUS, you might be able to fix the issue using this KB article. I haven’t heard of many problems yet myself, but I consider myself lucky knowing that I don’t have many Win 7 OS’es deployed (less than 50 of my total of around 300 computers).
Also, check this thread for updates, as it seems to be the most logical source:
Update: Use this script and the instructions on the above KB article link (Method 1, Step 2) to hopefully fix your broken SP1 installation.
sp1fix (Save this file, and change it to .vbs instead of .txt)