If you dig far enough into iOS's code, you'll eventually come across iPhone3,1, which is the AT&T iPhone 4, and the analogous iPhone3,2 (i.e. Verizon iPhone). It's nothing we haven't seen before, but then along comes iOS 4.3 with a handful of new mystery identifiers to spurn speculation -- namely, two new-generation iPhones (4,1 and 4,2) and three iPads (2,1; 2,2; and 2,3).
Its likely that the new iPhone models represent the GSM and CDMA version of the device and the three new iPad models are WiFi, GSM, and CDMA variants.
Any thoughts on what iPhone3,3 is?