Good news for music enthusiasts: Spotify's streaming music service is now free. The Spotify app has always been free, but you had to pay $10 per month for the opportunity to listen to on-demand music. That meant that you could request any particular song from their catalog. This, of course, was different from services such as Pandora and iTunes Radio, which let you indicate your favorite music but then stream similar music rather than the particular favorite you identified. Spotify's new free service for the iPhone falls somewhere in between. You can identify a particular artist, album, or playlist, but then Spotify streams the music in "shuffle mode," meaning that you get your favorite music but not a particular song at a particular time. The playlists available include those you've put together as well as playlists your friends have created.