The silence between the two largest instant messaging services may be about to end. AOL Time Warner Inc. and Microsoft Corp. have promised to align their instant messaging services, as part of their $750 million (U.S.) antitrust settlement.
[fromCBC News: AOL, Microsoft instant messages: 'Let's talk']

Why don't people just use one of the Jabber IM programs. Jabber is open source IM protocol. Find more information at Jabber.org or a neat client at My Jabber.