I like to see/read the documentation. The fact that there was none raised some flags. I Googled this and found some speculation
on what it was, but so far, no facts. Apparently it's raised a lot of questions since it's risen to #73 on items researched on Google in the past hour.
My general practice is to wait a couple days before I install any update to see if it causes any widespread problems. I am choosing not to install this patch until MS verifies it in some way.
I've found some articles today concerning this update. But nothing concrete. Cubic: KB976902 - "Black Hole" update Windows 7 Update to enable future updates.
Most of the people on the Microsoft Social forum are choosing not to install it until they too, can find some documentation. Undocumented Windows 7 Update (KB976902) - Norton Community