A primary application for many smartphone users is photography. Photo quality has improved a lot and most people aren't terribly demanding, but physics limits what a camera can do. Panasonic is exploring what a communication enabled camera can do with the Lumix CM1 - what if a smartphone was more along the line of a high end pocketable camera.
It is unlikely to have a huge market - for most people it is probably a bad idea. But something like this may be just the thing for those who find smartphone photography lacking and recognize the best camera is the one you are carrying.