When you’re browsing music, you can rotate iPhone sideways to see your iTunes content in Cover Flow and browse your music by album artwork.

See content in Cover Flow:
Rotate iPhone sideways.
Browse album covers:
Drag or flick left or right.
See the tracks on an album:
Tap a cover or .
Play any track:
Tap the track. Drag up or down to scroll through the tracks.
Return to the cover:
Tap the title bar. Or tap again.
Play or pause the current song:
Tap or . Or, if you’re using the included stereo headset, click the mic button.