In the opening scenes of the Wedding Date which was released on Feb 4, 2005 -- a bike messenger appears to be wearing an iPod Shuffle. Meanwhile, the iPod Shuffle was officially released on Jan 11th, 2005 at MacWorld Expo.
If true, this would mean the iPod Shuffle might have been floating around prior to the official release - unusual for the typically tight-lipped Apple.
If anyone has screenshots from the (still in theaters) movie, please post them.