GStreamer is a streaming-media framework, based on graphs of filters which operate on media data. This package contains front-ends to the other programs. These binaries were split out so that people can install both gstreamer-0.8 and gstreamer-0.10. The front-end know about version numbers, so you can install whatever version is most convenient, and have it use the correct gstreamer subsystem by saying e.g., gst-launch --gst-mm=0.8