iOS 4.1 Glitch Allows Access To iPhone, Bypassing Passcode

A glitch has recently been discovered in iOS 4.1 which affects the iPhone 4, 3GS and 3G.
This glitch allows the user to access the handset’s call history, voicemail and address book, even if there’s a pass code on the phone.
To do this, users access the handsets dialer application and then dial a random emergency number from the “Emergency Call” burron. Then quickly press the lock button after dialing that call.

Engadget have a detailed explanation of it here
After pressing the hardware lock button, a user can then access the call history, voicemail and address book on the phone.
Users can also hold down the home button to access voice control and play music from the iPod application.
Selecting “share contact” and then choosing the camera icon also allows users to view the photo album on the iPhone without having properly unlocked the device with the passcode as well.
What’s more, this glitch also works in the early beta builds of iOS 4.2 as well, so there’s something for Apple to work on anyway.