Beware, some users (including me) are having a problem after installing the update:

After clicking on one of the apps the Registration and Auto Update services run but even after completing them the Excel, Powerpoint and Word apps never start.A remove and reinstall to 12.0.1 have everything working again.

I’ll wait to try 12.1.0 a second time.  Here’s the solution:delete ˜/Library/Preferences/Microsoft/Office 2008/Microsoft Office 2008 Settings.plistdelete /Applications/Microsoft Office 2008/Office/OfficePID.plistthen start an app – put in serial number.after that it starts the MS update again and then it should work…