No doubt you know that this is very commonplace in Japan.
Here in Canada Mastercard has been trying a similar method of payment called PayPass, where there is an RFID chip in your credit card and you can pay simply by touching your card up against the area. I have one, and I love using mine. (In addition, PayPass/Mastercard the only way you can pay at our Tim Hortons coffeehouses without paying cash.) I have a feeling that their trial is going successfully and this will begin to roll out elsewhere.
I don’t think I want it attached to my cellphone, but the way it’s going now is perfectly fine with me. Although I do note, I would like to invest in an RFID shielding wallet, as I can easily use PayPass without having to take the card out of my wallet (but still being pressed hard against the scanning portion).