Pedro Melo (formerly of Portugal Telecom) notes that the IM silos are still holding up because they are not using XMPP for federated communications.
I agree that this is a sorry state of affairs. And as I commented at Pedro's blog I think that we need to strongly encourage more XMPP federation. But before we can ask big providers like AOL and Skype to join the federation, we need to get our own house in order by encouraging all the big XMPP deployments to federate! There are huge XMPP deployments at service providers like BellSouth and NTT and GMX, at big companies like FedEx and Sun and HP, and at lots of government agencies. What is stopping them from federating? Are they worried about security? Do we need to make it easier for services to deploy channel encryption over federated links? (I think so, which is why I've been working on the XMPP CA for the last 12+ months.) Do we need better tools to fight spam and abuse and denial of service? (No, we don't really have those problems, but we need to be ready when they arrive.)
If our federation is strong, then AIM and Skype and the rest will see the value in joining. But we need to have a strong federation story and reality first. So I think we still have some work to do, and I'm planning to focus on this quite a lot over the next 6 months. Stay tuned for details...