Here comes yet another dynamic theme for Windows 7 i.e. Bing Aerial, in which you get breathtaking views of the United States, delivered to your desktop.

The theme captures the best of Bing Maps aerial photography and updates automatically through an RSS feed.
Download: Bing Maps aerial imagery theme – United States
However, Microsoft has already released Bing Dynamic theme powered by Bing RSS that grabs images to be displayed as Desktop Backgrounds via RSS feed and receives a new photo from Bing every week for three months.