A new method to unlock an out of the box iPhone 1.1.3 has been made available. Only the Windows version is functional yet, the Mac version is still bugged.
All you have to do is download the tool ZiPhone and a GUI made by Unlock.no, and follow the short on-screen instructions.
For more information, see Ziphone on Zibree's blog and The Ziphone GUI
[translation by xavier]
