As Flash site's go, this is a good one (not fussy on the design, just that the Flash has been used well, not too in your face, and almost feels like a multimedia app rather than a website (in a good way ))
This sort of shake can be done with Javascript (not sure if they've used Flash for it instead)... checkout www.hotscripts.com for the javascript.
It's Java Script (look at the code, it's there).
Won't work if user has Java Script disabled on their browser. bobw probably has it disabled in Safari.