It looks like the cat and mouse game between Apple and the iPhone Dev team has started again.
According to an article on iClarified, Apple is now shipping a new BootROM called iBoot-359.3.2 with all the new iPhone 3GS’s that completely blocks the “24kpwn” exploit, which is being currently used by the iPhone Dev Team and others to jailbreak the iPhone/iPod Touch.
MuscleNerd, one of the members of iPhone Dev team also confirmed that the new BootROM update, would make jailbreaking “impossible” on the iPhone 3GS presently and also the immediate future. He also added that, this is the first time in the history of iPhone that they have seen them Apple do a bootrom update like this.
But, you know how the war between Apple and Jailbreakers work. We will probably give it a month or two before the iPhone Dev Team gets back with a workaround on how to jailbreak the new iPhone 3GS.