Just tried sending a message from my normal Jabber account to my Facebook Jabber ID - did not yet receive the message. Seems like it's not connected to the worldwide Jabber "network" (no server-to-server connections).

It's probably a technical shortcoming (think: a non-Facebook Jabber ID starts a chat with a Facebook user who is using the Web UI - the chat-with-a-Facebook-user assumption breaks here and would require the UI to be changed (no/different avatar, no Facebook page, etc..)). Nothing that can't be solved, though

Still, a nice option to connect with people who have no other IM accounts or only on proprietary providers (MSN, ICQ, Yahoo, ...). It's also a good excuse to set up Pidgin on a friend's PC ("so you can have Facebook on the Desktop") and then adding another open-network Jabber account to their Pidgin installation. It worked back in the day for converting ICQ users...