These are instructions on how to jailbreak your iPod Touch 3G and iPod Touch 4G using Greenpois0n for Windows. Greenpois0n supports iOS 4.1 and iOS 4.2.1 firmware. UseLimera1n if you want to jailbreak iOS 4.0, iOS 4.0.2.
Step One Open your web browser of choice and navigate to http://www.greenpois0n.com. Click the Windows link at the bottom of the screen.
Step Two When prompted save the download to your desktop
Step Three Double click the downloaded gp_win_rc5_b2.zip file then drag the greenpois0n.exe file to the desktop. Double click greenpois0n.exe from the desktop to launch the application
Step Four Power off your iPod then click the large Prepare to Jailbreak (DFU) button
Step Five You will now be instructed on how to place your iPod into DFU mode.
You will be asked to press and hold the sleep button for 2 seconds.
Continue holding sleep; press and hold home for 10 seconds.
Release sleep button; continue holding home for 15 seconds.
Step Six Once your iPod is successfully in DFU mode you may click the Jailbreak button.
Step Seven Greenpois0n will now jailbreak your device
Step Eight Click the Quit button once the software application has completed.
You'll notice some verbose mode text scrolling on your device.
Step Nine After the iPod restarts you'll notice a new Loader application on your Springboard. Press to launch it.
Step Ten Press to select Cydia then press the large Install Cydia button that appears.
Step Eleven Once Cydia has installed successfully you can remove Loader from your device. Press the Options button then press the Remove Loader.app button.
Step Twelve Reboot your iPod then run Cydia. Let it do all the necessary updates.
***A big thanks goes everyone who made this jailbreak possible.