If you are not familiar with Square, it is a mobile payment service (hardware and software) that hopes to change how mobile transactions are processed. Now available for iPhone, iPod touch, iPad, and Android devices, all you need to get going and accepting credit card payments is Square’s credit card reader. If you have been down the merchant account road before, you are probably asking how much the device costs, right? Square is giving out the reader, which plugs into the 3.5mm headset jack on your smartphone, for free. Their transaction rates are also pretty competitive at 2.75% of the transaction + $0.15 for all major credit cards. If you have always wanted to pay that shady guy off of Craigslist with plastic instead of paper, your dream might finally come true as this propagates throughout the wild. Check out a video of the service after the jump!