xmpp

After Google with GTalk (~ 180 million users) , now also Facebook (> 400 million users ) has switched its chat protocol to Jabber/XMPP ( pdf introduction). Now you need simply a generic xmpp client (like Adium, iChat, Miranda, Pidgin) and configure Facebook, Gtalk,.. XMPP is now the de facto the Standard protocol for Instant Messaging We should not use anymore chat systems/operators that use proprietary standards like Skype, MS Messanger and Communicator, ....