GStreamer
From WWR
GStreamer - is a set of multimedia routines which sit between a media player and a multimedia (sound and or video) source. It runs on several platforms, principally Linux.
GStreamer will become the default soundserver for the KDE desktop, replacing aRts. It can be used by several Linux media players including amaroK.
When you see GStreamer as the player on the Who's Listening page the listener will probably be using one of these Linux players.
