The law proved the users right, who are free to do whatever they want with their devices, but this does not stop companies from making it difficult for them, they just can’t accuse them of anything.
Thus, it has been discovered that the latest version of Apple’s mobile operating system includes a new mechanism to prevent this type of unlocking by verifying during the boot whether the signature of the baseband (the part of the firmware that controls the hardware of a mobile phone) matches what it should, i.e. whether it has not been altered in any way. If any discrepancy is detected, the iPhone will be locked in restore mode until it is connected to the computer and restored with iTunes.
Obviously, this will not prevent them from finding a way around this protection in the future, the question being when they will do so rather than whether they will succeed. For now, this only means that if you have an iPhone with version 4.1 and you want to release it soon for use with the operator you want, don’t even think about upgrading to version 4.2.1. Everything points to the new version of Ultrasn0w coming out this Sunday for all devices except the iPhone 4, which will still need a little more work, so patience.