The new deal between Starbucks and Square signals a new era of baristas knowing who you are before you enter the store. Starbucks announced it will use the Square payment system for all credit and debit card transactions starting this fall. Starbucks wants to encourage use of Square's app that lets customers pay for drinks without even taking their phone out of their pockets, using a GPS system. The stars may have aligned for this kind of technology, but the privacy issues can get tricky.