Jack Dorsey, who came up with the idea for Twitter and is now its chairman, has unveiled Square, his new start-up. The idea: anyone with a mobile phone can accept credit card payments.
Square makes a small square device that plugs into any gadget with an audio input jack, including an iPhone or iPod Touch, and turns the device into a credit card machine. Many small businesses cannot afford the steep fees that credit card companies charge. Square reportedly charges less, though it is not yet clear how much. The buyer signs the screen with a finger and gets receipts by text message or e-mail.