Now Microsoft has released a tool which allows you to set those awesome Bing background images as your desktop wallpaper automatically. Bing desktop fetch the image which is floating on Bing and then apply it as your desktop wallpaper.
The main aim of this tool is not to provide wallpaper to you but when you press Win+H it will open a Bing search box on your desktop so that you can make search without opening your web browser.
It do supports auto-complete feature just like Bing web client, and then it will open your favorite web browser to display search results.
This tool is only compatible with Windows 7.