Twitter launches mini credit card

Microblogging service, Twitter has branched into the market for electronic payments, unveiling a mini credit card swiper that plugs into the iPhone. Twitter's founder, Jack Dorsey, said that the device, the 'Square', is aimed particularly to enable small transactions, for paying "people like the babysitter, the car parker, the golf instructor".The small black square plugs into the phone's microphone, turning the iPhone into a card reader like the swipe machines widely used in US shops and restaurants.