Actually, Intuit came up with the idea for using mobile phones to accept card payments in 2007. They ran trials in the Bay Area in summer 2008, launched GoPayment properly in early 2009 (with a Bluetooth reader supporting various feature phones), and launched an iPhone app in August 2009. Inner fence had already created a card terminal app for the iPhone in late 2008 (albeit without a reader device).

Square announced their card reader in December 2009 and didn't actually launch until the following May.