Small business owner's could soon start accepting credit card payments using only their iPhone with some hardware/software from a company called Square. Square is a new startup from Jack Dorsey's (Twitter co-founder).

The payment system uses a small credit card reader that plugs into the iPhone's headphone jack, and a custom application that allows you to make cashless payments.

You should note that there are fees associate with using this service, so make sure you understand them before you get too excited about the prospects of the device.