I don't have a Gnex sold by Google, however from what I understand, all GSM Galaxy Nexus models are i9250, and the CDMA (Verizon/Sprint) models are i515. All accessories for the GSM models should fit, no matter if its a carrier-sold GSM or sold direct through Google.
I won't say for sure, but some cases for the i515 might fit as well, although the CDMA version is slightly thicker from what I've read. Batteries and battery doors are NOT interchangeable between i515 and i9250 models though.
Again, this is just what I understand from browsing the forums here and other sites as well. I could be wrong, but I'm pretty confident this is how it is. (And if I'm wrong, someone PLEASE correct me!!!)