If you use Facebook and XMPP, rejoice. You can now get spammed via your favorite Jabber client: iChat, Pidgin, Adium, Psi, Finch, Meebo or any other that allows you to configure custom server (gtalk not included).
Federationing not supported.
Probably a fail for privacy, but a win for openness.
Allow plaintext authentication: No
Your username is your "vanity URL" suffix, for example firstlast in http://www.facebook.com/firstlast – so create this alias if you didn't already.