Psi is a Instant Messaging application built upon an open protocol named Jabber, Psi is a fast and lightweight messaging client that utilises the best in open source technologies. Jabber technologies are highly extensible, so Psi is able to interoperate with other, proprietory messaging systems such as AOL's ICQ and Microsoft's Messenger. You can keep in contact with your friends, regardless of whether they use AIM, ICQ, MSNM, YahooM or even IRC. Psi has full support for Unicode so communication between different languages is not a problem.