Ever wondered how Gmail/Facebook chat works?

Web based IM clients are seem to be the flavour of the month at the moment. Gmail has had one for a little while now and more recently Facebook has added this to their already impressive stable of features. These are really cool, and rip all over the old form based chat rooms, but how do they do it without using any plugins, flash or the dreaded ActiveX componets?

Interested in finding details? k. Here where to find more...
http://technophiliac.wordpress.com/2008/05/28/ever-wondered-how-gmailfacebook-chat-works/