Microsoft Quietly Sunsets the Office Genuine Advantage Program
In fact, Ed Bott discovered that Microsoft mentioned the shutdown in a KB article, 917999. One sentence at the beginning of the article says: "The Office Genuine Advantage (“OGA”) program has been retired."
Additionally, at the top of the KB article, the article is now said to be "Retired KB Content," with a Last Review date of December 17, 2010. This implies that Microsoft retired OGA just a few days ago.
It's unclear why Microsoft made this move. Windows Genuine Advantage (which is required for some downloads, like Microsoft Security Essentials) is still working, Bott noted. Additionally, Activation is still required for the Office product, as it is for Windows, as well.