I saw this article today at TUAW (the unofficial apple weblog). Looks like Square ( one of the first point of sale card swipe systems for the iPhone) is moving upmarket from their current dominance in the small food service vendors like gourmet food trucks and coffee shops.
This company is growing fast due to it's simple interface and ease of use. In case you missed it, they also cut a deal with Starbucks last year that will allow you to use the iPhone "wallet" app as a payment system. More about that deal here. If your interested, you can go here to get the Square Wallet app and start paying with your iPhone at any vendor that uses Square.