A question that came up a number of times at Lotusphere was when MSN would be supported by the Sametime Gateway. It seems clear from the responses that while there are technical issues, the business issues of Microsoft agreeing to the federation is the real blocker. While this is going on it looks like AOL is moving to support XMPP. According to a comment left by an AOL Architect
Thanks for blogging about our commitment to openness. We’ve been working really hard over the past few years in making all of our services more open and standards based, working with the SIP as well as the Jabber/XMPP communities. Our XMPP gateway at xmpp.oscar.aol.com, which we’ve been working on for a while now, is just one approach we’re tinkering with. As you pointed out, though, this particular server at xmpp.oscar.aol.com is a test server, so I wouldn’t count on it being reliable or even continuously available until we put some more work into it to bring it up to our standards.
So while MSN continues to be proprietary, and for now not willing to federate with IBM, AOL is moving to be more open and compatible. If AOL moved to a stable XMPP implementation it could eliminate the need for provisioning for gateway connectivity to AOL.