You don't wanna change something on the harddisks, but wanna safe the changes. So you boot from Live-CD and the changes are redirected to the USB-Stick. Puppy Linux does it that way*. I wanna see it in Fedora. :D *http://puppylinux.com/development/howpuppyworks.html *http://puppylinux.com/development/pup2layers.png