How Apple Cheats by Mark Sands:
Say what?! Did Apple seriously grant access to four of their native apps by hardcoding their bundle identifiers? Yep, they sure did.
In fact, you don’t have to do anything special to verify this. If you change your UIPopoverController Hello World project’s Info.plist bundle identifier to com.apple.iBooks or com.apple.itunesu, then voilà, It works!
Really, it’s in iOS platform interest that Apple own apps and third-party apps play in the same league.