Yeah, founded a startup based on this idea in 2006 or so, called WeBrowse. The technology wasn't quite ready although I got pretty far with a prototype based on DOMMutationListener and XHR.<p>Pretty clearly something like this needs to exist, and it will probably not be nearly as useful as it's inventors think it will be. Screen-sharing is more general, and the niche for low-entropy real-time synchronization of browser state <i>feels</i> pretty small right now. But who knows? Heck, I thought the iPad was going to be a giant flop.