Master hacker P0sixninja announced that the jailbreak will come more quickly to the iPhone 5, the time required would be less than the time needed to download the jailbreak iPad 2. Chronic Devteam have found 5 bootrom which can be exploited at the chip used A5 iPhone iPad 2 and 5.
Jailbreak reliable difficult to apply in the A5 and iPad 2, because bootrom chop found in the A5 and it takes hard work to find things that can be exploited. That's why it took four months to create a stable jailbreak for iPad 2. But therefore, Chronic Dev Team has found 5 bootrom, so that this exploitation-based software, so even if the hardware revision will not be able to do much to prevent the jailbreak.
You may remember that IOS beta 5 has been terjailbreak just hours after the announcement at WWDC, so the concern is only in the iPhone hardware 5. But now it seems it was not a problem anymore. The problem is when the iPhone 5 was released?