RedSn0w Can Jailbreak iOS 4.2 GM: Problem Discussions
We reported earlier that Apple has released its iOS 4.2 GM (Gold Master) to iPhone developers and is now available for devs to download, well now we have a little info about the latest RedSn0w update.
We know that you can already jailbreak iOS 4.2 using the latest RedSn0w update but apparently you really need to know what you are doing because any doubt at all should tell you to stay away.
If you update the iPhone to iOS 4.2 GM could potentially stop you from unlocking it forever (Not to sure on this one so please do comment below).
The Dev Team has said:
Today Apple released to developers the GM seed for 4.2. Tinkerers will find that yesterday’s redsn0w jailbreaks today’s 4.2 GM seed, simply by pointing redsn0w at the 4.1 IPSW (rather than the 4.2 one). Right now it mostly only makes sense for JB app developers to do that because many apps (including Cydia itself) need to be updated for 4.2. However, if all you want to do is enable afc2 (to use iFunBox or other file browsers), or to tweak settings like Battery % and Homescreen wallpapers, then go for it (if you have valid paid access to the GM seed). Be sure to uncheck the Cydia box, though! Ultrasn0w unlockers should stay very far away from this!!
If you do decide to go ahead with it please do let us know how you get on, we want to know all. Thanks
Source — iPhone Download Blog