Three weeks ago, we told you about the untethered jailbreak from Comex on iOS 4.2.1 for iPhone, iPod touch and iPad which was scheduled to release by Christmas, but due to some issues Comex was not able to finish his job. So the iPhone Dev-Team had an alternative plan which is the "back up plan" using an old firmware iOS 4.2b3, but this firmware caused some piracy issues, as it's not available for public, it's only available for developers.
L0ung3f1Y asking: @comex or freakin release a jailbreak that does not require 4.2b3So, if Comex releases the untethered jailbreak for iOS 4.2.1 then you will need to preserve your iOS 4.2.1 IPSW and hashes to be able to get untethered jailbreak for the upcoming iOS 4.3
MuscleNerd replying: So if @comex were to develop 4.2.1 untether, we warn all to save their 4.2.1 IPSWs for 4.3 untether via Monte
More explanation ? iOS 4.2.1 Redsn0w jailbreak is based on Limera1n bootrom exploit by Geohot, but this exploit can't make untethered jailbreak itself, it needs some help to make untethered jailbreak which is a kernel hack, This is precisely what Comex wants to get.
While we are able to jailbreak all our iOS devices using Redsn0w 0.9.7, the dev-team may preserve the new Comex's kernel hack to untethered jailbreak all upcoming iOS for iPhone, iPod touch and iPad, so you have to save the iOS 4.2.1 IPSW file and its hashes to enjoy untethered jailbreak as long as possible. [BlogsDNA]