ReadWriteWeb says it’s already common in Asia.

I told me wife when we got our iPhones last year that some day we’d be paying with our phones instead of credit cards. She wasn’t entirely convinced, but I think the only real argument she had was that if you lose your phone you lose not just your contacts, calendar, apps, etc, but you also lose your payment device. I don’t really see how that’s any more of a problem than losing your credit card… All you do is call your company and cancel it.

The argument I see is that if your credit card bill melds with your phone bill, we’ll probably stop getting the same kinds of rewards from credit cards. I’ve been able to save quite a bit of money for retirement simply by using cards that provide rewards with companies where I have my IRA accounts.

Of course, the RWW article doesn’t say if the charges on an NFC-enabled phone accrue to your phone bill, or if it can simply be used with an existing credit card account.