Scanning documents with an iPhone or other smart phone can be tricky because of lighting and the impossibility of holding the camera parallel to the document. Scanbox has a solution and is completely funded now on Kickstarter. It is made of durable cardboard, snaps together with magnets, and folds flat. For $25 you get the deluxe version with LEDs for enhanced lighting.
I scan documents on my iPhone using JotNotPro and store them on Dropbox and Evernote. Scanbox will produce even better images.