How to Jailbreak iphone 3G on iOS 4.0

Alright, it's about time, you have finally made the decision to free your iPhone of all of the restrictions that have been placed on it by Apple. And here is your Step-by-step guide to jailbreak that iPhone.

First thing's first, you will need to get a few things in order:
We will jailbreak using Redsnow, which will work with both the PC and the Mac.
You need to download the jailbreak utility called Redsnow  0.9.5b5-5 for Windows or 0.9.5b5-5 for OS X.
You also need to download THIS firmware which is the 3G 4.0 Firmware for the iPhone
Or THIS firmware for the iPod Touch 2G

Now that you have those you are ready....or are you?

1. Plug in your iPhone/iPod to your computer and turn it off, then run the redsn0w program, once it opens click on "browse".

2. Through "browse", find the 4.0 firmware IPSW, select it and click on "open".

3. redsn0w then processes the IPSW for you, wait until the "Next" button shows up on the bottom of the redsn0w program and click it.

4. After you click "next" redsn0w does it's magic and starts jailbreaking your iPhone/iPod.

5. It will then give you options. The most important ones to select are "Install Cydia", "Enable Multitasking", "Enable HomeScreen Wallpaper", and "Enable Battery Percentage". After check-marking these, click "next".

6. redsn0w will remind you to have your iPhone/iPod both OFF and PLUGGED IN to the computer. Assure both of these are true and click "next".

7. After you click "next", redsn0w will talk you through putting your iPhone/iPod into DFU mode (it's a little tricky so don't get discouraged if it takes a couple of times).
             1. Hold down the Power button for 3 seconds
             2. Without releasing the Power button, hold down the Home (center round) button and power button for 10 seconds
             3. Without releasing the Home button, release the Power button, and hold the Home button for 29 more seconds.
             4. When redsn0w starts working it's magic, you can release the Home button.

8. redsn0w will flip through a few different screens and then tell you that it's done and the rest of the process takes place on your device. At that point you click "finish" and let your iPhone/iPod do the rest.

9. After your iPhone/iPod reboots, you are good to go. Cydia will be installed and you are free to browse the plethora of amazing apps and features that are now available to you.

I hope this guide has helped you achieve your goal of jailbreaking your iPhone 3G/iPod Tough 2G. If you are having difficulties or need more help feel free to contact me.