The only way I see mobile payments via NFC becoming a big thing here in the states is if Apple adopts the technology into their devices. And I'm seriously serious here.
If Apple placed Nfc in the next iPhone then it'll take off.
iDoubt Apple will negotiate a 30% cut of all iPhone NFC transactions though...
Seriously though I agree; especially if they negotiate a cross-marketing advertising campaign with certain national merchants or one of the card processing companies. It could be another instance where Apple isn't the first to the party but their entrance into the market really brings it mainstream. (mp3 players, smartphones, tablets)