Consider me about 2 days late to this game, but it looks like Facebook finally turned on XMPP chatting. This means that as opposed to the horrible, godawful, REST-driven javascript chat client, you can chat with a desktop client! To those familiar with dropped or duplicated chat messages, trying to IM someone online to find that they're actually offline, and the other oddities that come of Facebook Chat, this should be a welcome change. To make things better, Facebook is attaching to the same open protocol Google uses, so existing chat client software can easily get on Facebook.

Details on how to attach are provided by Facebook, but it's generally just "Add an XMPP account as <user>@chat.facebook.com with your Facebook password" Since I found this out at 3am, I really haven't had any way to test the chat functionality's reliability. I remain confident, however, that Facebook got this up correctly.