Apple's last processor, the A4, was built upon ARM's Cortex A8 CPU which was a single core CPU. The latest - the A5 processor - is built upon ARM's Cortex A9 dual core CPU, which is the biggest hurdle in finding the bootrom-level exploit in A5 devices.
Pod2g, who is sitting on the recently found untethered jailbreak for Apple's A4 devices, is also getting help from his team to test the jailbreak on different devices running iOS 5.
I read the comments on the blog, and I know that a lot of people are waiting for the A5 jailbreak. Also, I know there are tons of people out there with A4 or even earlier devices who wants the untether now and don't care about it could be interesting to wait A5 is finished to release or even 5.1, so that we don't waste an exploit that took me months to find and develop, Pod2g wrote on his blog post.
I need to focus on A5 and hope I can find a path quick, and I have the feeling that chronic-dev could help me, the blog post added.
However, time is running out for Pod2g as Apple is expected to release the iPad 3 - the iPad 2's successor - in the first quarter of 2012 and the iPhone 5 in the latter half of 2012. Rumors are rife that the iPhone 5, which could succeed the iPhone 4S and the iPad 2, will run on newer operating systems and an advanced processor, which tech circles call the A6.
Meanwhile, Pod2g is optimistic about his efforts and said he is working hard to release the A5 jailbreak.
I'll put all my energy from now on on the A5. Hope I don't disappoint, Pod2g said in his blog post.
Recently, iPhone Dev member, MuscleNerd, released a semi-tethered version of the jailbreak for iOS 5. MuscleNerd released Redsn0w that jailbreaks all Apple devices running iOS 5, except A5 devices (the iPhone 4S and iPad 2), immediately after the release of iOS 5.