Allowing the user to have an area on the 'phone to store and edit files would be sweet. However, I guess the iDisk is Apple's idea of this...
i was thinking more along the lines of eye candy. not to the point where it screws up functionality and ease of use, but other phones are trying to steal customers with their drag and drop widget type stuff and i think apple will do something (maybe no widgets, but something) to make the interface feel fresh.