New iPhone credit card payment service SquareUp has finally been unveiled, and we’ve gotta say, it’s got our attention. The brainchild of Twitter co-founder Jack Dorsey, SquareUp aims to be a simple, sleek, inexpensive, and charitable credit card payment processing service. It works on the iPhone and iPod touch, in conjunction with a credit card reader that plugs in to the audio jack. You get payer verification, receipts that can be sent via email or text message, and receipt signing using your finger. Even cooler, in our opinion, is that Square will donate one penny of every transaction to a charity of the seller’s choice.

If Square plays their cards right, they will be a force to reckon with in the small business arena. The service is in limited beta right now, but Square says it’ll be fully open in 2010. We’ll see if we can’t get a beta account to give you a better look at how it all works.