My iPhone 5's will not auto backup to iCloud or iTunes. My iPod Touch & iPad on iOS 5.1.1 all backup as expected. My other iPod Touch that used to backup automatically hasn't backed up automatically since I upgraded it to iOS 6. My Genius bar specialist said its a known issue to be fixed in an update, bit I can't find any Apple documents or support articles confirming it. All of my iOS 6 iPhones backup manually just fine.