We've been tracking Twitter founder Jack Dorsey's Square since May when we first got the details on the new mobile phone payment service. Today the company unveiled its website for the first time, and they continue to test the product in private beta. Dorsey twittered that the site is live moments ago. The idea - let people quickly and easily accept physical credit card payments from their mobile phone. A small device attaches to the phone via the headset/microphone jack. The device gets the power it needs to send data to the phone from the swipe of the card, and sends the information over the microphone connection.