Hi, been having this problem for ages. I have all non-free extras installed for xine and amarok as far as I can tell. Trying to play a a stream from jamendo.com, I get a 'no suitable demux plugin found' in amarok. In xine or mplayer it just doesn't play at all. The only app that plays streams is the mplayer plugin for firefox, which is ok, but you can't jump to the next track, and it always only plays 10 seconds of the first track in the playlist.
Edit: got it working in xine, but not in amarok.. ah well. Anyone else have a problem with amarok and streaming?