encoding:
nope
You CAN encode from a live source or an uncompressed avi, but you can't pipe forward to the producer (yet).
Apparently "Someone here wrote a test encoder on Linux using libavcodec as input source, allowing input of all libavcodec supported formats, but it has not been completed to a state where it can be distributed"
Multiplexing:
You can mux using the stadard tools (I think they only were PORTED to windows and are native Linux apps)
Playback:
Mplayer will play it if you have the real dlls (included in the essential codec pack) in the codecs folder