does it mean facebook doesn't want to be a walled-garden anymore? interesting...
No. They would need to support Federated XMPP for that. Federated XMPP is why I can chat to people who are logged in to Google Talk, even though I'm using my own XMPP server and am not using a Google account of any sort.
Yeah, besides the apps listed there you can integrate Facebook chat with Digsby as well (on Windows)