The bouncing/rocking technique

I know all about image scrollers and how to make it work in many forms but I found this one unique, a technique to make it bounce/rock before it comes to rest. Does anyone know how to do this?

Check out this site:
http://www.mitredesign.com

You’ll have to click on ENTER, then WORK, then click on PORTFOLIO. Any clues on how to get just this bounce to work in AS would be appreciated.

Thanks,
Gazzer :cowboy: