Use Your iPhone to Accept Credit Card Payments

Innerfence has an app that allows you to use your iPhone to process credit or debit card payments. At first glance I thought it sounded like an application for drug dealers and hookers but I've read it's intended for people selling things at farmers markets, craft/art fairs and other street vendors. The app is 50 bucks and there are setup, monthly and transaction fees so you'd need some profit margin and volume to make it worthwhile.