I always thought this would be Apple's next plan as well. "Pay with your Itunes account" or something like that.
That doesn't seems very Apple like move, they don't like to mess with ugly systems and integrate their products with anyone.
They have a good place to do that, but I doubt that they'll go that way.
But Steve isn't there, and Apple moves might be unexpected.
They could first allow people to exchange any amount of money with friends for free, add it to their mobile app so that everyone has it anytime. Other apps are doing that, and that's very useful.
And they should buy Stripe, bind everything together, displace amex, visa and mastercard.
Or may be that's the plan, but it's best to be silent ?