Listed with a model number of GT-I9020A, the handset is strikingly similar to the Samsung I9020T currently supported by T-Mobile. The Web site specifically mentions AT&T and references the carrier's UMTS 850/1900 network bands, but with no announcement from Google or AT&T, this remains strictly unofficial at this point.
Given that Sprint recently unveiled its version of the Nexus S, it would not surprise me to see a Verizon variant offered down the road. Samsung has been making it a practice to offer different iterations of the same device, especially those in the Galaxy S series.
I'm very interested to see how AT&T handles this "pure Google" smartphone, considering it blocks the ability to install applications and games from anywhere but the official Google store front (even the Amazon Appstore is out). Will it loosen the reins a bit and allow users to download apps from outside of the Android Market? Or will it continue to lock things down? We'll have to see.