Microsoft UFO to fly in Phoenix?

The second clue in Microsoft's "Vanishing Point" puzzle to launch Microsoft Vista will be unveiled at 4 p.m. Saturday in Phoenix, which they say was chosen for "high visibility and clear skies." Promised is "a stunt that everyone in the Valley [will] be talking about by Saturday night."

Perhaps a UFO flying over South Mountain with the Microsoft logo on it?

UPDATE (January 13, 2007): It was supposed to be simultaneous sky-writing in Phoenix, Los Angeles, Miami, and Sydney, but I'm not sure if it happened in Phoenix as scheduled--today was a very overcast and cold day.