Service Pack 1 (SP1) for Microsoft Office 2007 contains significant security and stability improvements, as well as improvements to its performance. It also incorporates all previously-released fixes into one update.
According to officials, Microsoft will not be pushing the new Office SP1 to users via Windows Update this time round. Instead, Microsoft plans to go the Automatic Update route three to six months from now. It will also give users a 30-day notice before doing so. This should be a relief for administrators dealing with Microsoft's regular patches released on the December 11th Patch.
You can get Microsoft Office 2007 SP1 here.