Thanks, I've been there already, but one could read that phrase as referred to international iPads, not US. BTW, the fact that's on US Apple website should suffice...
As a matter of fact, since I'd buy two of them, for a considerable amount of money, I'd rather see first-hand smoking gun, since returning the product would be a bit difficult...
For the user that's gonna come over here on July: I'm in contact with some guy in H3G carrier ("3 Italia", that is), which assured me they're gonna have some sort of iPad-centric offer by the end of May. It should be PAYG, by all means. You could safely ditch AT&T international data plan, if your iPad supports other carrier's micro-SIMs.