These are instructions on how to jailbreak your iPhone 4 and iPhone 3GS on iOS 4.3.3 or iOS 4.2.8 (Verizon CDMA) using JailbreakMe.
If you are already on iOS 4.3.3 or iOS 4.2.8 you can skip the first five steps of this tutorial.
*Remember that updating to iOS 4.3.3 will update your baseband and perhaps ruin your chances of an unlock. Use TinyUmbrella (Mac, Windows) to update the iPhone 4 to iOS 4.3.3 without updating the baseband.
Create a Pwnage folder on your desktop and place the iOS 4.3.3 or iOS 4.2.8 (Verizon CDMA) ipsw in it.
Connect your iPhone to the computer and launch iTunes.
Select your iPhone from the list of devices on the left
Hold down the Option (Mac) or Shift (Windows) key and click the Restore button.
Select the iOS 4.3.3 ipsw from the Pwnage folder on your desktop and click Open.
Once your iPhone is running iOS 4.3.3, press to launch Safari from your desktop.
Navigate to http://www.jailbreakme.com and press the Free button.
Press the Install button.
Safari will now close and Cydia will download and install.
Press to launch Cydia and enjoy your jailbroken iPhone!