gta02-core

AFAIK, the gta02-core project from OpenMoko (not yet in production last I checked) is the one that gets nearest the idea of an open phone. Not only there are free drivers for every piece of hardware it uses (it is basically a OM GTA02 with the problematic components swapped with more free ones, thus the name), but also the full schematic is available without a NDA. IIRC, it uses a Telit GSM modem.