Just a quick note:  from the graphs below — see my post from Dec 14th on the top 20 music 2.0 sites, including graphs that automatically update thanks to compete.com — it looks like imeem has begun its upward trajectory again and, coupled with another decline at PP, is now in the #1 position.

Other big trajectories:  MOG is now approaching the size of Live365, Qloud has jumped significantly (now at nearly  225k uniques/month), and SoundFlavor (which features a PP or Seeqpod-like streaming MP3 search engine) has seen two solid months.