The Sonos Controller for iPhone is a free application that turns your iPhone or iPod touch into a full-fledged Sonos Controller that works over your home WiFi network. Plus, it fits in your pocket so you can carry it with you all over the house. Best of all, you can download it for free on the App Store in seconds. Simply touch the screen to pick a room, point and flick to choose a song, and hit play to enjoy.