We need to be able to buy them easily, store them securely, exchange them with smartphones.
You got the gist of it in this one sentence !
After a bunch of deep economic / sociological philosophy posts and a couple of libertarian / utopian / hippie posts in this thread, here's one that's simple and makes perfect sense.
That doesn't require a new currency. Just easier and lower-cost methods of transferring an existing one. Like DoCoMo, Vodafone, Dwolla, Square, Google, etc. are doing.