The nearest Starbucks to me is 44km away, which makes me think that if you were able to deliver, it would likely be cold. Also, I can't say that Starbucks coffee is nice - seems more like coffee flavoured milk than an actual drink. You can also make perfectly awesome coffee at home, for cheaper than your delivery cost, and you get to use your own cup.
For that reason, I'm out. Nice looking iPhone app though.