XMPP and AIM
After the Google/AOL agreement in late 2005, speculation regarding the interoperability between AIM network and GTalk network was rampant.
A screenshot of a new GMail client shows some AIM integration.
Unfortunately, the image shows "Sign out of AIM" which means that they seem to be doing a multi-platform client, and not XMPP federation. That is to say: you can login with your AIM credentials and talk with your AIM friends, inside the GMail interface, but you cannot use your GTalk account to talk to AIM buddies.
Of course, this is just a screenshot someone took somewhere. Their camera could be of the Photoshop brand. I do hope so.
If this is really what's going to happen, then the IM silos are still holding up.
