This was posted in the official Google Blog on Tuesday, March 29, 2005:

google.com/googleblog/2005/03/ ...

I almost missed it because it was posted before the "Puzzling images" blog – and so appears after it – on the same day.

Aah, OK. I think I even read it but thought it was connected to their old stock functionality (the plain link). Tony, if you ever want to be a guest-blogger on anything here, let me know.