iPhone App Reviews

Okay, first upgrade your iPhone/iPod Touch to firmware version 3.0 using iTunes. The update costs $10. Then head over to the dev-team blog here, and download redsn0w. Unzip the download onto your desktop. Find your iPhone/iPod Touch firmware on your computer located

C:\Users\*USERNAME8\AppData\Roaming\Apple Computer\iTunes\iPod Software Updates

on windows.

and here on mac

home/Library/iTunes/iPod Software Updates

Remember the location of this file. Make sure it is 3.0

Plug your device into iTunes and put your iPhone/iPod Touch in DFU mode by holding the power and home buttons down until the ipod shuts off, then count to 2 and release the power/top button but keep holding onto the home button. It should now be in DFU mode.
Open up the redsn0w app or .exe on mac and windows resectively.

Follow the instructions. Once you get to the part about turning your ipod off, you already did this by putting it into DFU mode so just hit next. Follow the rest of the instructions in redsn0w and your iPod/iPhone should now be jailbroken with 3.0!

This guide was written with the help and guidance of this post http://www.ipodtouchfans.com/forums/showthread.php?t=203161