Requires iOS 4.2+. Not for iPad

Change ringer volume on the app switcher bar, as well as the music volume.

Tap the speaker image to change it to ringer mode. Tap again to change the music volume.

Only for iOS 4.2 and above.
Only for devices that have a ringer. (All iPhones and iPod Touch 4th Generation only)

No new icons are added to your homescreen, and there are no options to configure.

See More Info below for Screenshots