Well, this isn't good. A new security flaw has been discovered in the iPhone, one that allows anyone to bypass the lock screen to access the phone app. This contains the address book, voicemail and call history.
In order to get around the lock screen, you hit the "Emergency call" button, enter three pound signs, hit the green call button and immediately press the lock button. That's it. Go ahead, try it!
Hopefully Apple will patch this one up ASAP.
Via Threat Level