An anonymous reader writes "Facebook today began prompting Facebook Messenger for Windows users as well as Facebook Messenger for Firefox users with a message saying the apps are shutting down next week. Without much of an explanation, the company plans to kill off both on March 3. It appears that Facebook is no longer interested in developing desktop apps. The Android and iOS versions are still alive and well."
You can always connect to their IM service using a generic XMPP client like Pidgin
(too bad Facebook doesn't federate).