Dwolla is a payment network that will change the way businesses exchange money online. The sites new payment network can cut costs currently being charged by other providers. Dwolla uses a $0.25 max transaction cost on all money transfers, instead of the standard 2-5% fee. Dwolla is designed to handle any size of transaction and utilizes innovative technology that can be integrated into a plethora of payment devices. Dwolla for Windows phone 7 is under development from a 3rd party developer and its soon coming to marketplace as well. The above images are some of the screenshots of the app. Dwolla has an open API, so If you are a developer then you may try to build a better client..
Source: Dwolla Blog