Yes, this is because for "Media Player" and "MPlayer", headphoned can only send a "Pause" signal, but this is just like a press on the "Play/Pause" button (i.e. when it's paused, unplugging unpauses the playback). This even happens when you don't have Panucci running.

The only application that provides a "Pause if it's playing, do nothing otherwise" command is Panucci (for obvious reasons . At least I have not found D-Bus calls for pausing the media player or input commands for MPlayer that do what I want. An alternative would be to have headphoned go check by itself if Media Player / MPlayer are currently playing something back and avoid sending the "Pause" signal in certain cases.

Again, the code is open and patches are welcome