Could be something, could be nothing, but an "iPhone3,1" mysteriously popped up in the usage records of a Bay Area App Store developer. If you'll remember, the "iPhone2,1" turned out to be the 3GS.
The 3,1 phone was spotted in an analytics report from November for the iPhone app iBART.
This isn't the first time something with that ID popped up on the rumor radar. In August, 3,1 was discovered hiding in iPhone firmware files. However, as MacRumors notes, this is the first time the marker's been "seen" gallivanting out in public.
Also noteworthy is the timing of the discovery: In October 2008, Apple starting testing the 3GS in and around the San Francisco area. [MacRumors]