Florian Jensen blogged about an AOL test server that lets you connect to AIM and ICQ accounts using XMPP, an open protocol also used by Google Talk. This tutorial shows how to connect using a client that supports XMPP, but you shouldn't expect too much from an experimental project.
Edwin Aoki from AOL confirmed the news: "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. (...) 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. In the meantime, keep your eyes open for more announcements from us soon."
Justin Uberti, a former AOL employee who now works for Google, is hopeful about the future. "Right now you can only connect to the AIM/ICQ network using this gateway, there is no XMPP Federation. This means that you cannot talk to users on any other IM network at this time, including Google Talk. Hopefully AOL will add support for XMPP Federation in the near future."
For now, Gmail lets you chat with your contacts from AIM or ICQ, but you still need accounts on those networks.