Mobile payment startup Square confirmed it received a strategic investment from Visa. Square produces a credit card reader that connects to the headphone jack of an iPhone, iPad or other mobile platform. The Square application on the device accepts the credit card information from the reader and processes the payment on the fly. It's an easy way for small businesses to accept credit card payments with minimal hardware requirements and a small 2.75% per transaction fee. [Past TUAW coverage of Square is here. -Ed.]
The company is growing -- in the first quarter of 2011 alone, Square processed US$6
