In what may prove to be a pivotal breakthrough for the mobile payments space, Square has signed up Starbucks for its platform, a deal that will allow you to use Square to pay for your mocha, yes, but will also make Square the processor of credit and debit card transactions for the coffee shop chain, a move that will significantly expand the Jack Dorsey-backed company’s scale. It’s also a roll of the dice for the brand, too: Starbucks will also invest in Square, and CEO Howard Schultz will join the company’s board. As you guys may know, Starbucks is already leading the way on the point-of-sale front, with mobile apps that store Starbucks cards that can be scanned anywhere. This is one step further. So, who will follow their lead?