It's only been a couple days since we first heard about Visa's involvement with Square, but the credit card giant is already making its mark on the mobile payment startup. At the Visa Global Security Summit on Wednesday, Square Security Lead Sam Quigley revealed that the company will distribute an encrypted card reader this summer, which will work exclusively with its mobile payment app. The current reader theoretically scans credit card data to any app, but the encrypted version will only work with Square, which should alleviate