A new Jailbreak tweak named Parallax is now available in Cydia store. The tweak allows you to use a panoramic wallpaper and set it as background on your iPhone Springboard. The app allows you to flick through the wallpaper by scrolling left and right once it is set as background.
All you have to do is upload on your iPhone some widescreen wallpapers (the ones that iOS would usually “cut” to fit the smaller screen of the iPhone) and select the auto scroll speed (or manual adjustment) in the tweak’s preferences inside the Settings app.
The app seems very fast and stable as you can see a video of it below. It is not recommended to install it on older 3G and 3GS devices.
The tweak is available in Cydia store where you can buy it for $1.40. Enjoy the wallpaper scrolling behind the icons.