Google Wallet, a major push for Google on its Sprint-backed Nexus S 4G, has been a non-starter on the newer Galaxy Nexus — there have been ways around the block, but there hasn't been anything officially supported. That just changed, though, because it turns out that unlocked GSM Galaxy Nexuses with AT&T SIMs installed are being offered access to the app (and so is the AT&T version of the Nexus S, we're hearing). It's not clear exactly when this changed, but it seems to have happened this week — a good sign that the carrier is going to be open to supporting Google Wallet going forward despite its investment in the competing ISIS initiative. The Verizon model still doesn't have access, unfortunately, but it's possible that pressure from AT&T's move will light a fire.
Update: Though you can't see it directly from the Market, it turns out that there's a way to massage it into installing on Verizon versions of the Galaxy Nexus as well; Droid Life has the details.