Increasingly for me the music player is the browser. I don't know which library is used when a browser plays audio, but where once I was protective of my music collection, now I find the web playback through pandora and grooveshark to be far more frequently used. For the next generation, my daughter only knows youtube as a music player; the separation of music from video seems to be a concept only readily grokked by those currently over the age of 12.