Windows 7's mission: reclaim the netbook territory.
If anyone still has doubt, check out the Technet homepage. The second featured article on Windows 7 is about using USB drive to install Windows 7 on a netbook, which by the way has been common for Linux for quite some time.
Netbooks may well be place for the beginning of the end of Windows' dominance in the client OS market. With Android on netbooks around the corner, Microsoft clearly sees the writing on the wall. There's really no time to waste for them, and it'll certainly be very interesting to see the battle.