To get started, you make a regular, Square-enabled purchase at a participating store, at which point a text-message receipt is sent to your phone that prompts you to install Card Case -- we skipped this step, as this was just a demo. Once set up, we were introduced to the Card Case, holding cards for the participating stores -- only 50 spots in five cities, for now -- and an "Explore Places" button that offers access to a directory of participating outlets. We selected a nearby cupcake stand, clicked "open tab" and picked our poison: a miniature red velvet cupcake, in this case. The merchant picked our name from a list of open tabs, charged the tiny treat to our card, and a receipt was promptly pushed our way. After the transaction was complete, we went back to the cupcake card in the Card Case, and there was the receipt. All in all it was a painless process, but, then, so is whipping out a real wallet to make a purchase. The new Square setup is available now at 50 different establishments in New York, LA, Saint Louis, San Francisco, and DC, and the company says it will curate the list of participating stores, much like Apple does apps.