Are you asking if you can use your iphone as portable data storage? I know that Belkin had an adapter for the iPod that would let you transfer images off a CF card onto the iPod's hard drive. IIRC, the time to transfer a full card (somewhere in the neighborhood of 2GB, which was typical at the time) exceeded the iPod's battery life and the device was pretty much useless.
One of
these would be a more useful accessory.