You can boot it on one system, shut it down and then boot it on another. It will auto-detect hardware. Boot it on the first one again and it will boot up nice and quick as it remembers which drivers to load on a per machine basis.
see here and wiki and see the recorded BUILD presentation here
Now you can take the office computer home on a stick!
Now the school can give Johnny a USB stick with Office and IE9 and the curriculum software apps on it and say - do your homework on this.
It also supports VHD booting, so you could simply copy a VHD onto a stick and hand it out.
In the final release, you can 'clone' your copy onto a USB drive and make a Windows To Go drive using the integral Win 8 app, but I suspect you may need quite a large USB drive to do that.
On a USB 3 Flash drive, the performance is supposed to be almost as good as a fast hard disk - 32GB+ is recommended!
The steps are simple.
1. Format a USB drive as a single NTFS primary partition (if using a flash drive use a fast one of at least 16GB if you just want to try or 32GB or more if you want to play with it a lot!) - I recommend trying a spare USB HDD first just for speed. Format it as NTFS and make it active.
SEL DIS 1 (assuming disk 1 is your USB drive)
ONLINE DISK (in case it is offline)
CLEAN (this will erase your USB drive)
CRE PAR PRI
FORMAT FS=NTFS QUICK
Or safer - use RMPrepUSB to format it as NTFS and make it active .
2. Use ImageX to extract the image from the Windows 8 Developer Preview ISO:
syntax: Imagex /apply (DVD):\sources\install.wim 1 (USBDrive):\
ImageX /info I:\sources\install.wim
ImageX /apply I:\sources\install.wim 1 G:\
You will need to obtain ImageX from the WAIK or other source as it does not appear to be on the Preview ISO.
3. Make the USB drive bootable :
syntax: BCDBOOT (USBDrive):\Windows /s (USBDrive):
e.g. BCDBOOT G:\Windows /s G:
See here for my quick 'how to'
[Edit] The 64-bit Server versions work (but these are not publicly available) and the 32-bit Desktop version works (publicly available as Developers Preview 32-bit) but I could not get the Desktop 64-bit Developers Preview version to work[/Edit]