Although Square has had the service available for some time, this partnership with Starbucks will likely propel Square forward in it's leadership of the mobile payment arena.
The premise is simple: GPS recognizes you're in Starbucks, your image appears on the cashier's screen and you place your order. Aside from an initial, one-time setup of your account that's really about it. You can expect integration Starbucks rewards as well.
Here's a semi-awkward video of how it might work ›
The question now is what will happen to Starbucks' mobile app?