Daniel Amitay, the developer of the Big Brother Camera Security app, ran an interesting survey of his application's users. He added some code to anonymously record passcodes of iPhone owners who use his application.
With this little test, Amitay was able to record 204,508 passcodes from as many devices, giving him the opportunity to find out what the most used passcodes are. If you are using any of these passcodes, you might want to change this right away in order to increase the safety of the information on your device...