One of the most requested feature by Windows Phone users is the ability to have Bing daily image in their lock screen. Its now possible by yet another homebrew project from Jaxbot of Windows Phone Hacker. The app basically allows you to set a dynamic background, either the Bing background of the day or a custom slideshow, and the app will update the wallpaper with a background task.
Just for a reminder, this app requires full root access. So you need a customÂ ROM to enjoy this app.
Find more details on this app here.