Picasa-like wallpaper pan-and-scan?

[dewalist]

Picasa has a really neat screensaver that takes photos and does a smooth zoom-while-panning-then-fade trick to make it looks like the pictures are moving slightly. I know it is a ripoff of a wallpaper changer that Apple has (or had) in their OS. I was wondering if anyone knew of an app (or even better, a live wallpaper) that offered this behavior.

Thanks!