Jack Dorsey, one of the co-founders of Twitter, has just launched a new project called Square. It’s a mobile payment service that seems to cover a lot of bases. A small square dongle using the 3.5mm jack (from which the company earns its name) allows for credit card swiping. Sellers can get receipts sent to their e-mail and SMS for approval if need be, and everything is stashed securely in the cloud for future viewing. Buyers can sign for purchaces on a touchscreen, and if the seller needs additional security, can get a verification popup asking “Does the person buying your doodad look like this?” if the buyer has a Square account. If that’s not enough, they also toss in some philanthropy: Square will donate a penny to a charity of the seller’s choice for every transaction they make. Neat stuff all around. No word on a release date (though beta is opening soon) or device compatibility, but Android and iPhone are shown off prominently.