wallpapers???

hey, when i was at the mac store when i bought my macbook, all the mb's there had an animated wallpaper, how do i get it to mine?
it was animated, kindof a slideshow but better
btw: my favorite leopard wallpaper; http://farm3.static.flickr.com/2008/2166489070_9a0d1ee9e8_o.jpg

It was either a screen saver running on the desktop, using wallsaver:
Download Wallsaver for Mac - Run screensavers as desktop background. MacUpdate Mac Software Downloads

Or it was a folder of pictures with the change pictures option on

Or, its some secret application apple uses to entice people into buying their macs.;D

BTW: For awesome Desktop Pictures visit:
InterfaceLIFT: Wallpaper sorted by Date

thnx, for the wallpaper site mostly tis a good one;P