I'm assuming you'd attach a name to your order, as well as have the drink charged to your credit card. I think this is a bit silly considering you're already at Starbucks. Is walking 3 feet to the register really that taxing? Ordering this way wouldn't eliminate the line either, since there are only so many people behind the counter and iPhone orders won't be carried out before in-person orders.
Please, someone tell me why this is a good idea.
Coming soon? Buy some coffee, then some music, hmmm...then some more coffee.