Exactly the same philosophy as with OSX Lion and having an alternate UI within the OS for browsing 'apps' and running them full screen like a tablet, the way he demoed having the metro UI next to the classic win 7 UI was cool if a little ugly, like they've just thrown the metro UI on top of the old UI instead of truly integrating them. Next a linux distribution that can run android apps will be announced, oh wait, it already can! (but there's no alternate UI like this yet, just you wait it will happen!)
Maybe Windows will finally be nice to use on the go. So far, Windows is terrible without a mouse and kb compared to other OS's.