Listen enough to Rdio on the desktop and you'll know your friends' taste in music when they're fellow subscribers. As of a fresh update to the iOS app, you'll also appreciate any musical kinship while on the road. iPhone users receive an overhauled playback view that shows just which friends have listened to that favorite album or playlist. They'll also have a more pleasing view in mid-play that blows up the album art and downplays the interface. There's no word on similar treatments for the Android app, but the odds have increased that you'll at least have the web fallback for social l