How To Hack IPOD Touch 4G 4.2.1
Use redsnow 9.6 b5. download 4.2.1 ipsw from firefox. After that run redsnow in XP Compatibility mode AND run as administrator. follow the instructions and your done.
NOTE: THIS IS A TETHERED JAILBREAK SO IF YOU REBOOT OR YOUR BATTERY DIES YOU MUST RE-RUN REDSNOW AND CLICK JUST BOOT TETHERED RIGHT NOW.
If uou have done this now you can go to www.greenpois0n.com and download and run greenpois0n and you will have an untethered jailbreak!!! works awesome over a redsnow tethered jailbreak.