Incidentally, there was an older project floating around to actually use Jabber, which is an open-source version of ICQ/AIM/MSN/etc.
I am not sure if this is relevant here but this DotGNU (http://www.dotgnu.org/) announcement was published yesterday:
[DotGNU Announcement]The DotGNU Project officially endorses the use of the Jabber Protocols
"The DotGNU Project hereby officially endorses the Jabber protocols (as described in the Internet Draft draft-miller-jabber-00.txt) as a mechanism for routing information via DotGNU webservice technologies."
http://subscribe.dotgnu.org/pipermail/announce/2002-May/000004.html
Andreas