AIM Google Talk Federation now live

I hope it does, as it might help XMPP take off as a federated network, and not as merely the foundation of GTalk implementation. I wish Yahoo, MSN Messenger and Skype (for IM) would do the same.

The other party has to be willing to work with Google too.

Who's to say it was Google who stopped? Skype actively prevents anyone else from making a client and I can easily see MS not wanting to play along with Google.

As a result of the AOL Time Warner merger in 2001, the FCC ordered AOL to open up its instant messagning protocol to stop blocking applications like Trillian and Adium at the time from creating an interoperable method.

In 2001, AOL represented something like 90% of the instant messaging market with its combined networks of both ICQ and AIM. Building AOL compatibility then meant a whole heck of a lot and it's taken more than a decade to get to some kind of interoperability.

I wish Skype had some sort of market share large enough to justify the FCC pushing Microsoft to do the same thing. Interoperable video calls are really important.

Works for me.

That is significantly harder. Consider a graph (as in, graph data structure) of IM users. Communicating between an AIM and an XMPP user is a single line, and even though the two nodes are on different services it's not that hard to make work. Almost by definition, both services have very similar semantics for what an IM is, and stuff like presence converged a while ago enough for interop.

Now, consider a conference. Let's say AIM_A and AIM_B wish to conference with XMPP_X and XMPP_Y. Now there's six entities; the four users I just mentioned, and the conference rooms that are supposed to be reflections of each other. Conference rooms actually have complicated protocols for creating and managing them, fundamentally. Hooking them up to each other is very non-trivial. What does it even mean at the protocol level for XMPP_X to try to kick AIM_A out of the conference? You need a lot of infrastructure to make this work, almost none of which exists because it requires both conferences to cooperate, or a lot of implementation by one side or the other to be able to directly connect to an entirely foreign network on a foreign protocol. None of which the proprietary networks are likely to do.

Without cooperation on both sides this is basically impossible.