by PC World The cat-and-mouse game between Apple and a cadre of hackers continues, as Apple is reportedly now shipping iPhone 3GS units that are jailbreak-proof. Several hackers specializing in iPhone 3GS jailbreaks are saying that the well-known 24kpwn exploit is no longer viable, because Apple is now shipping iPhone 3GS models with a new bootrom that can resist the hacking technique, according to iClarified . If you think that last sentence sounded like a bunch of technical nonsense, you're not alone. So let's break this jailbreaking jargon down: Death of the Hackable Bootrom A bootrom is a computer chip used in mobile phones to check the device's software when you turn it on, and makes sure the device hasn't been tampered with. I'm not clear on what the iPhone bootrom can do if it detects a problem, but a Blackberry bootrom can shut down the device if a problem arises. To use the jailbreaking metaphor, think of the bootrom as the prison guard who checks that all the inmates are where they should be, before letting the prisoners go about their day. Hackers used to get by the bootrom using the 24kpwn exploit that would make the guard think nothing was wrong, and everything was running normally within the iPrison. Before the iPhone 3GS came out, some hackers were worried the 24kpwn exploit wouldn't work. Fortunately for these computer rogues, Apple was not able to change the bootrom within its supply chain before the 3GS was launched. But all that may have changed, since iPhone 3GS devices reportedly began shipping last week with an updated bootrom. Nicknamed iBoot-359.3.2, it is believed the new chip is not susceptible to the 24kpwn hack. Basically, the iPhone 3GS now has a smarter prison guard. So what does this mean? Without a hackable bootrom, the new iPhone 3GS is not jailbreakable, which means that you cannot use software on the device that is not Apple approved. Another term thrown around a lot is 'unlocking' your device. An unlocked phone can run the device on any compatible cellular network , instead of whatever network the phone was originally tied to. The hack for unlocking the iPhone requires modifications to the baseband, which is the system responsible for phone calls and Internet access. I'm no hacker, so I can't tell you definitively if the new bootrom means the iPhone 3GS is impossible to unlock as well as jailbreak; however, an unlock is dependent on some operations that happen when your device starts up so my assumption would be that new iPhone 3GS phones are resistant to unlocking as well. So is this the end of jailbreaking and unlocking the iPhone? Probably not, those iPhone hackers are a pretty smart and crafty bunch. But the clock is ticking. Let's see how long it takes for them to come up with a solution to Apple's latest roadblock.