Chronic Dev Team released the Greenpois0n, Jailbreak for iOS 4.2.1 Untethered and its is available to download as link mentioned below. You can use Greenpois0n to jailbreak iPhone 4, 3GS, iPod Touch 4G, 3G, 2G and Apple TV 2.
Greenpois0n is available for Windows and Mac OS X
Greenpois0n for Windows :
GreenPois0n RC6-final.zip, Mirror
GreenPois0n RC5-b4.zip
GreenPosi0n RC5-b2.zip
Greenpois0n for Mac :
GreenPois0n RC6-final.zip, Mirror
Greenpois0n RC5-b4.zip
Greenpois0n RC5-b3.zip
Greenpois0n for Linux [Not Available Yet]
See also:
- How to jailbreak iPhone 4 4.2.1 untethered using Greenpois0n
- Jailbreak iPad 4.2.1 Untethered using GreenPois0n
- How to Update iPhone 4 to 4.2.1 without updating baseband