I would love to see a slight modification to the design of their reader hardware. Keep the audio interface, obviously. But design a small plastic frame that the reader can fit into that fits flush against the edge of the top of the iPad/iPhone. Make it a bit longer with slightly sloped internal edges so that its easier to guide a credit card to the scanner. This will also have the benefit keeping the reader from swiveling around while in use. Actually sounds like a Kickstarter project if Square doesn't come out with it themselves soon.