A new link discovered by Sander (one of the excellent Googling Googlers who keeps tabs on what they see at Google) in the main Google Accounts page reads "Change authorized websites".  The link points to www.google.com/accounts/IssuedAuthSubTokens and displays a page that tells me "there are no third party sites authorized to access your account".
He points out the possibility this could be related to an article I wrote back in February regarding the X-GOOGLE-TOKEN which would allow websites to accept a Google account as a method of authentication.  Considering the website this link points to (IssuedAuthSubTokens), I would think this scenario is likely

Account Upgrades.

Dear Valued Customer,

Due to great expansion within the premium service and a need to keep
your websites running as fast as possible! We are upgrading our
infrastructure that hosts your site(s). This upgrade will massively
improve your web site speed / accessibility.

The upgrade will involve us moving your websites to a new data center
and onto new more powerful hardware. While this process could be quite
disruptive we will be working to minimize any interruptions.

The migration of the server your site is hosted on will start on.

25-09-2007 (19:00GMT) and will complete by 26-09-2007 (02:00GMT).

During this time, we ask that you try to not make any major site changes.

This upgrade will improve general stability / speed / accessibility of
your site and we are sure you will appreciate the significant

Best Regards

Byethost Services