Finally... certainly took a while. Interesting given discussion of Facebook offering traditional email services as well.
Every day people send more than two billion chat messages to each other on Facebook. Today we're making it easier for people to extend those conversations with their Facebook friends to instant messaging clients beyond Facebook.com. Facebook Chat now supports Jabber/XMPP, the open standard for instant messaging. Now developers can integrate Facebook Chat with their Web-based, desktop, or mobile instant messaging products.