I like being able to only carry my phone, keys, drivers license, and debit card a little too much to add another pocket turd in to the mix. One of the best things about getting the original super-expensive iPhone was being able to get rid of so much junk I'd usually carry around with me in exchange for one device. I wish you could use your phone to pay for things like you can in Japan, I hope one day in the future to only need to carry my phone as it unlocks everything for me and serves as both a debit card and ID.
Hmmmm I would seriously reconsider a data plan/phone bill if I could pay with my phone like in Japan and have ID as well. Cool idea.......carry my wallet around in my phone. Of course who's to say this couldn't be implemented within a pre-paid phone as well?