iPad SDK adds ability to set home screen wallpaper
Apple has added the ability to set the wallpaper for iPad Home Screen in the latest beta 3 of the iPhone OS 3.2 SDK. Such functionality is not currently available for iPhones and iPod Touches.
On iPad in the Photos app when you select an image, you can choose to set it as the "Lock Screen" or "Home Screen" wallpaper (or both). It is also possible to have different images as the lock screen and home screen wallpapers. Here are the screenshots: