The rocking guys at FFmpeg have just released version 0.5, the first release in eons! Congratulations!
You don’t know what FFmpeg is? Go read about it on Wikipedia. For most people, FFmpeg is what provides the horsepowers to their media applications, in the form of codec and format implementations, and as such it acts as a critical cornerstone of better-PR’ed projects such as GStreamer, Mplayer, Xine or VLC.