This is a great write up and explanation of something I've been wanting in iOS for a while now. A file.app would allow me to use the iPad as a true workstation away from my desktop. I love the idea of a file picker, and with some of the implementations or iOS 6 with regards to the inclusion of image insert inside of mail, and more access to documents in the cloud I wouldn't be surprised if something like this was on the horizon for when they announce the iPhone five. Or at least I can dream ;-)
http://www.imore.com/2012/05/22/ios_6_files_app_documents_picker_icloud/
http://www.imore.com/2012/05/22/ios_6_files_app_documents_picker_icloud/