Note: I am aware that Zack posted a previous guide, but I've found that it is outdated, as BlackRa1n is no longer being updated by Geohot.
THIS ONLY WORKS FOR IOS 4.2 OR BELOW!
Download LimeRa1n here (http://limera1n.com/limera1n.exe) for the Windows version, or here (http://limera1n.com/limera1n.zip) for the Mac OS X version.
Step 1: Download the latest version of limera1n from the link above and save the application on your desktop.
Step 2: Double click on the limera1n exe to launch the application.
Step 3: Please ensure that your iPod Touch is connected to the computer.
Step 4: Click on the "make it rain†button.
Step 5: You will see that limera1n puts your iPod Touch in recovery mode. Immediately after this, follow the instructions.
Step 6: Limera1n will be prompt you to press both the home and power buttons.
Step 7: Limera1n will be then prompt you to release the Power button. Continue to press the home button.
Step 8: You will see that limera1n has put your iPod Touch in DFU mode. Continue to press the home button.
Step 9: While limera1n performs the exploit, you will see the limera1n logo on your iPod Touch.
Step 10: When limera1n has successfully jailbroken your iPod Touch, you will see “done†and get the following message.
Step 11: You need to restart your iPod Touch. You will notice that there is a new app called limera1n installed on your iPod Touch.
Step 12: Launch the limera1n app to install Cydia on your iPod Touch. Select Cydia and tap on the Install button to download and install it.
Step 13: After Cydia has been installed, reboot your iPod Touch.
Step 14: You should find Cydia on your iPod Touch’s homescreen.
Step 15: Have fun. :)
Step 16: *Optional* Uninstall LimeRa1n. (Not suggested, useful if Cydia won't start.
Jack.
Does this work for 4.2.1?
Quote from: Mute on April 07, 2011, 07:15:50 PM
I've never jailbroken an iPhone/iPod, but I've been reccomended to use Pwnagetool to jailbreak it. Dunno why though. :P
Pwnagetool is for tethered jailbreaks.
Greenpois0n is untethered meaning you jailbreak it and you are good.. nothing else needs to be downloaded and stuff, whereas a tethered jailbreak requires pwnagetool or some other tool to be downloaded to make your device function properly.
I recommend Greenpois0n because it is for 4.2.1 too and is easier I'd say. (Untethered+user friendly)