http://www.youtube.com/watch?feature=player_embedded&v=ZDb9JCv3NlA
Thanks to Portable Workspace, an upcoming feature introduced in the successor of Windows 7, Windows 8 will enable deployment scenarios involving nothing more than USB flash drives. Essentially, Microsoft has expanded Windows 8 installation options not only to HDDs (hard disk drives) and SSDs (solid-state drives), but also to USB storage devices.
Portable Workspace is a Windows feature that allows you to run Windows from a USB storage device, the software giant reveals.
To create a Portable Workspace, you need access to Windows 8 Enterprise Edition installation files and a USB storage device with the following features: the device appears as fixed storage media [and] there is sufficient space for a full installation of Windows 8 Enterprise Edition.
A user who got his hands on the recently leaked Windows 8 Milestone 1 (M1) Build 7850 put together a video demonstration of the Portable Workspaces installation process.
(http://i51.tinypic.com/jioprs.jpg)
Update:
There is pwcreator.exe which is 'Portable Workspaces Creator', it says 'Portable Workspace is a Windows feature that allows you to run Windows from a USB storage device.'
it has a wizard:
1, To create a Portable Workspace you must specify the location of the Windows 8 Enterprise Edition installation files. These files can be located in a folder or on a Windows installation disc.
2, This device will be formatted before you can create a Portable Workspace. All data and all volumes on the device will be deleted. Please back up your data before you continue.
3, Please restart your computer to boot into your portable workspace
4, This might take several minutes.
5, Continuing will format your device and delete all volumes. Any data stored on the device will be lost.