SP1 for Vista 64-bit on Windows Update?

I'm getting (and reading) sporadic reports that Microsoft has made Windows Vista Service Pack 1 (SP1) available to Windows Vista 64-bit users via Windows Update.

Anyone else seeing this?  I'm not seeing it yet, but I'll update this post when I find out more.

Seems like one of two things might have happened:

• Someone at Microsoft's flipped the wrong switch (a possibility)
• Microsoft has decided to make SP1 available to those who have the prerequisite updates (KB935509 which is an update for Ultimate users only, KB938371, and the troublesome KB937287)

If SP1 is indeed inbound, before you install you might want to check out this knowledge base article which made an appearance yesterday on Microsoft's site: Information about programs that are known to experience a loss of functionality when they run on a Windows Vista Service Pack 1-based computer.  This information applies to 32-bit and 64-bit systems.