Back in 2005, Google came out with Gtalk, which was a text and voice based chat application. Soon thereafter in early 2006 the same capabilities, minus the voice feature, were integrated right into Gmail. Today, we now have the ability to not only use voice but also video right inside Gmail.
In true Google style, all of these features are of course free and were designed using internet standards ( IE. XMPP, RTP and H.246 ) so that other networks and applications can incorporate what Gmail and Gmail chat has to offer.
All that is needed is a plugin that you can download straight from http://mail.google.com/videochat which works in the following browsers: Firefox 2.0 +, Internet Explorer 6.0 +, Safari 3.0+ and of course Google Chrome. When installed you may have to restart your browser but other than that there is nothing else you must do in order to start waving to your friends across the world.