iOS 6 Beta: First Look
Settings: Do Not Disturb
When the new Do Not Disturb feature is enabled, and an incoming caller is not on the Allow Calls From list, or an active white/black list, you aren't even notified of the call. However, you do have the option of allowing repeated calls to ring the phone. This is especially handy in the case of an emergency; if a caller calls more than once, he'll get through.