Making an Ubuntu Live USB

"How to make a USB flash drive function as a Ubuntu (or Kubuntu, Xubuntu, Edubuntu) Live CD. The base file system is ext3, it boots using extlinux and supports the same hardware as the Live CD. Instructions on how to update the Live CD and modify it's contents are also given. For the entire document /dev/sda is the USB device.

Booting from a USB device is ofter faster than from CD and USB drives are easier to carry. You should know why you want and or need this. We used Kubuntu 7.04 Feisty Fawn as our image for booting and a Gentoo system for building on."

http://edoceo.com/liber/ubuntu-live-usb