EDIT: This post was edited on 11/28/2007 to mention KB944752.
The update is live at:
It will also be offered via Microsoft Update.
The article covering this update can be found here:
Note: We have a workaround for those of you that have had issues with some services not starting up automatically after RU5 has been applied (not all systems are affected). For more information, please see KB944752.