Hi John,
They are using Javascript to call the server behind the scenes. I've been
using this on most of my sites for a couple years now because all my
clients
*hate* post backs. If you want to see how they do it download Fiddler:
http://www.fiddlertool.com/fiddler/
You'll be able to grab the s.js and app.js Javascript files and see
exactly
how it is done. Note that since you already hit the site those files
won't
come over again because you have them cached. So clear your Temporary
Internet Files then run Fiddler and browse to the site, you'll then get
fresh copies sent to you.
Also this blog mentions that it was the work of the MSN team:
http://blogs.msdn.com/ASanto/archive/2005/03/11/394262.aspx
You might want to go to their blogs and request them to create a blog
entry
explaining how it works. Finally, things just keep getting cooler over at
http://www.start.com/2/ . Good luck! Ken.