It appears that PocketNow has some insight into the world of Google and their distribution of the newest Google phone - the Nexus S. As far as they (and now we) can tell, three versions of this phone have made their way through the FCC: the original GT-i9020, then the GT-i9020T and GT-i9023. Evan Blass of Pocketnow did a bit of investigating and has discovered a fourth, which thanks to the Bluetooth SIG, he's been able to identify a model that's not appeared in any other databases - GT-i9020A.
The reason this version is suspected to be the AT&T version is the directions the other models are going in:
i9023 - Europe. And according to Best Buy,
i9020T - T-Mobile US
i9020A -- more than likely AT&T
This would also follow as the first Google phone, the Nexus One, was released on T-Mobile and AT&T first as well, never quite reaching Verizon or Sprint. What do you think? Reasonable?