The patent (6449344), originally filed in 1997, and granted in September this year, gives AOL instant messaging subsidiary ICQ rights as the inventor of the popular IM Internet application. The patent covers anything resembling a network that lets multiple IM users see when other people are present and then communicate with them.
"The claim is it's a system where you have a network; you have a way to monitor who's on the network; and if you want to talk to them you hook them up," said Gregory Aharonian, publisher of Internet Patent News Service, a newsletter that's critical of technology patents. "If you're doing something like that, you're potentially infringing."
Invalid Patent: prior art, Zephyr
iKimbo (www.ikimbo.com) received a patent on a method for inviting people to join "communities" which include chat or instant messaging systems.
Invalid Patent: Users of Groove will be familiar with the idea of "inviting" someone to join a "community" of discussion. Quite a variety of other systems have implemented similar capabilities in the past, (eMeetings, invitations to Yahoo Groups, etc.) however, for obvious reasons, none of these are cited as prior art. iKimbo is clearly looking for a hunting license. Licensing fees will undoubtedly be lower than the cost of invalidating this bad patent.
United States Patent 6,519,629 iKimbo, February 11, 2003
Microsoft received a patent on "Activity Monitoring" for Instant Messaging systems. This patent would seem to cover the MSN Messenger messages that say: "Sally is typing now..."
United States Patent 6,519,639 Microsoft, February 11, 2003
You can find more patents here