Dynamic BackgroundÂ homebrew app got updated to v2.0. This homebrew app allows youÂ to change your lock screen background dynamically on your Windows Phone 7.x devices. Windows Phone 8 will have this as a native feature.
- Automatically changes the lock screen wallpaper periodically
- Create a slideshow to cycle through, or
- Use the Bing daily wallpaper
- Customizable time intervals
Interop unlock with root privileges
Source: Windows Phone Hacker