I installed the latest Windows 7 RC because I wanted to try it out and I needed to do something with my media computer. When I first went to log in I saw the login screen background and thought it was great! Unfortunately, you can’t set that picture as a background within Windows 7 (it is only a login screen image).
Using a tool called ResHack I was able to extract the image from the dll. Feel free to download the image below.

They have a lot of “tall” images and I am guessing because they are expecting tablets to start taking a more dominate market share. The tall image makes the screen much more “paper-like”
Please be nice to my bandwidth. And if I happen to get this post taken down (not sure why I would when it is a public beta) I will try to find a mirror somewhere.