I have used it before, it works great. However, and I didn't use it very long because the second monitor had to leave my desk, I couldn't get it to work with an aero taskbar. I have seen screenshots of it that way though, So I am sure it is possible.
The current build of windows 7 that is out on bit torrent that i saw was just building on windows vista. Microsoft hasn't leaked a version with a new kernel...Yet.