In his last update to Big Brother Camera Security, Daniel Amitay added some code to record common user passcodes. Because Big Brother’s passcode setup screen and lock screen are nearly identical to those of the actual iPhone passcode lock, Daniel figured that the collected information would closely correlate with actual iPhone passcodes. Out of 204,508 recorded passcodes, the top ten most common were:
[1234, 0000, 2580, 1111, 5555, 5683, 0852, 2222, 1212, 1998]

Source: amitay.us