Today everyone gets a Two In One Day update for the Bing Dynamic RSS Themes. Updated backgrounds were released for both the original Bing Dynamic RSS Windows 7 Theme and the Bing Aerial Maps Dynamic RSS Windows 7 Theme.
These have grown into a couple of great collections so be sure to download the themes to get all the updates on your Windows 7 PC.
Bing Dynamic RSS Aerial Imagery Windows 7 Theme
Original Bing Dynamic RSS Windows 7 Theme