It is known that the updated version of Redsn0w 0.9.7 will allow you to untether iOS 4.2.1 Jailbreak using iOS 4.1 instead Of 4.2b3. The “Monte” technique is successfully ported back to iOS 4.1 by iPhone Dev-Team.This will enable users to untether the iOS 4.2.1 jailbreak on iPhone, iPad and iPod touch without having 4.2b3 SHSH blobs saved on Cydia.
The upcoming Monte based Redsn0w 0.9.7 update will be most likely for both Windows & Mac users. It will enable you to just untether iOS 4.2.1 jailbreak using iOS 4.1 IPSW files only.
The next step will surely be to port this update forward for iOS 4.3 beta versions.
Here is the recent tweet by MuscleNerd about Redsn0w 0.9.7 Update:
Turns out the 4.1-blob version of Monte wasn’t so hard http://is.gd/3yMmRb… Next step: porting it forward to 4.3beta!
Using the new version of Redsn0w 0.9.7 which is going to be released for Mac OS X and Windows you can untether your iOS 4.2.1 jailbreak using iOS 4.1 IPSW files.