Portable Windows 8 Feature
Ever since Windows 8 has been leaked, a bunch of new features have been found. One of the features is called "Portable Workspace Creator". This new feature allows you to run a bootable copy of Windows 8, just like you could with a Linux live CD. The storage device for the portable workspace must be at least 16GB, so a USB drive would work best.
A few questions arise from the new feature. It is unknown how many portable copies you can make or if there are any limits such as an expiration date. It is also unknown if you can install Windows 8 from the portable workspace.