Hard Drives For Still Cameras?

Apple iPods can hold so much music because they have actual micro-hard drives built in. And Hitachi has squeezed micro-drives into compact digital-camera-storage/index.html">flash cards. So why aren't there storage/index.html">camera-storage/index.html">digital still cameras with hard drives?
The answer may have to do with use patterns, convenience, size and cost. Still photographers like the convenience of removeable media, and using cards keeps the size, weight and cost of the camera down. And it allows the camera to be treated much rougher, too.
Video camera makers such as JVC and Toshiba have released digital video cameras with hard drives, instead of digital tapes.
So a digital still cam could be in the future.