Twitter's chairman and one of its co-founders, Jack Dorsey, is launching a totally different company which could transform the way people buy things as much as Twitter transformed the way people communicate.
The company is called "Square" — it's a little plastic device that plugs into your iPhone and allows anyone to accept a credit card payment. (They're working on the applications for it to work from Blackberrys and other mobile devices).
It's remarkably simple — like PayPal on the go. The person getting paid plugs the black square into his or her iPhone and swipes the payers credit card through a slot. The last four digits and expiration date of the credit card show up, and the buyer signs his or her name with a finger. You can input your e-mail address or phone number to receive a receipt via e-mail or SMS.