We've gotta hand it to Square. The mobile payments company has just signed on its biggest partner to date--Starbucks. Yep, with the new deal, customers will be able to pay for their orders with the Pay with Square app in the US, which means they won't even need to bust out a card or cash. Square will also be processing all Starbucks credit and debit transactions. In addition to Square being accepted at Starbucks locations, the deal also sees Starbucks investing some $25 million as part of Square's current financing round. Starbucks CEO Howard Schultz has even joined the Square board of directors. Yeah, this is a big deal. Other Square partners include FedEx, Staples, and Walgreens.

So, when will you be able to start paying with Square at Starbucks? The company will launch the functionality this fall across 7,000 US locations.