Topic: Looking for Popover code

Hi Folks,
I'm in a bit of bind trying to find some code that will allow us to display an in frame pop over that is cookied to only display once to a new user. Basically a welcome to the site, we're currently in beta with a small image.

I've seen this technique used quite extensively recently. e.g. Digg Videos.

and was wondering if anyone has a code snippet that might get us started.
Very much appreciate your help!