The cause of the proble is that you have changed your facebook privacy settings to “Turn off all apps” (under “Apps and Websites”). This will disable your ability to send messages via jabber, as well as to receive messages sent via jabber. ….To fix the problem, simply enable apps again….. both you *and* the facebook friend you are sending messages to need to have apps enabled for jabber communication to work
I do not use facebook. I value my privacy: it is not a commodity. Please use an OTR capable client, and enable OTR (auto start / or require). Psi+ is such a client and is cross-platform. Unfortunately if you are not installing via PPA (ubuntu) you must manually install the Psi+ OTR plugin (unpack from 7zip archive into plug-ins directory, options plug-ins enable)
Remember: you used an email address to signup for facebook. So, yes, you do have an email address. When you invariably ask “hey, what’s your facebook?” and the privacy aware friend replies “I don’t facebook,” be sure to follow with “what’s your email? oh, and what’s your jabber?”. play well together nicely.
Seth Wisely said: adjust facebook “privacy” settings to allow external XMPP, but better yet ditch facebook entirely as it is the LEAST common overlap of other mature technologies.. unless you like being raped for profit then signup for all google “free” services, too