I have just been tipped off by one of our readers who has got a reply from Chpwn, confirming that Cydia is now ready for primetime use on iOS 4.2.

iOS 4.2, at least from what information we have so far, is slated for release this Friday and it’s going to be a significant update for iPad (not so much for iPhone / iPod touch, though). And of course, there’s going to be a jailbreak to accompany the new iOS version. Here’s all you need to know.

The iPhone developer and hacker behind Sn0wbreeze has confirmed that Cydia has started saving SHSH Blobs of iOS 4.2 betas for the next untethered jailbreak on the final version of iOS 4.2.

As we posted in our guide on how to jailbreak iOS 4.2 GM on iPhone 3GS; Cydia and a lot of jailbreaking apps are completely broken. Both Cydia and JB apps will, of course, eventually start working and if MuscleNerd’s tweet is anything to go by, hackers chpwn and saurik are burning the midnight oil to get it working as soon as possible.

PwnageTool bundle for jailbreaking iPhone 3GS on iOS 4.2 GM has been released. You can use this bundle with PwnageTool 4.1.x to jailbreak your iPhone 3GS (old bootrom only), while preserving your old 05.13.04 baseband so that you can unlock it using Ultrasn0w.

Apple has already seeded the final Gold Master version of iOS 4.2 to developers. Public release is looming near. Once the new firmware is out, Apple will stop signing the old firmware, which will make it impossible for you to get SHSH blobs for iOS 4.1.

Geohot’s Limera1n used a userland exploit from Comex to make an untethered jailbreak for all iOS 4.1 devices. While Apple cant patch the original bootrom based Limera1n exploit, the userland exploit though can be patched easily by a firmware upgrade such as iOS 4.2.

Apple has seeded the final GM release of iOS 4.2 to developers. The recently released Redsn0w 0.9.6b2 (based on Geohot’s Limera1n) can jailbreak all of the current iOS devices on iOS 4.2. This has also been confirmed by MuscleNerd of the iPhone Dev Team.

The iPhone hacker and developer behind Sn0wbreeze has managed to jailbreak iOS 4.2 for iPad. This of course has been achieved using Geohot’s untethered bootrom level Limera1n exploit. The image below shows full root access using MobileTerminal on iOS 4.2 Beta 3 for iPad.

Just a couple of hours back, iPhone hacker MuscleNerd tweeted to say that he thinks that iPhone Dev Team has found a way to extend current untethered jailbreaking tools to work on all A4-processor based iOS devices.

The SHAtter exploit based GreenPois0n tool is all set to arrive on October 10. But unfortunately, it will only jailbreak the fourth-generation devices like the iPhone 4, iPad, iPod touch 4G and the Apple TV 2G. This limitation is because of the nature of how the low level bootrom exploit SHAtter works.

Even though Chronic Dev Team hasn’t announced the tethered status for the SHAtter based GreenPois0n tool yet, but if this tweet from the well known Cydia developer is anything to go by, GreenPois0n is most likely going to be an untethered jailbreak for iPhone 4, iPad, iPod touch 4G and Apple TV 2G on iOS 4.1.