Not only possible but a killer idea really!
No, I do not think it was about interaction. I believe it is about us living in a world of convenience. I am not a fan of Starbucks but if I want coffee there are about 10 Starbucks that I can drive to before I hit the one and only Peet's Coffee across town. I prefer Peet's then Coffee Bean & Tea Leaf. Starbucks is a necessary evil. I also have two I can walk to in under 5 minutes right @ work. The point is, if I can order before I get there or while I am walking that would kick ass. The coffee can be sitting on the counter when I walk in, I can grab, tip, and walk out. Yes I tip--I'm a jackass like that. Of course that idea takes the OPs idea slightly further, but still. Now if I can get within a certain distance of the shop and then order that is still nice. Again, not about interaction, just about convenience.
Now if I could schedule an order for a certain day at a certain time I would certainly find a reason to need an iPhone...well kind of. I doubt I'd buy an iPhone just because of that. Regardless, it is a nice idea.