This is going to be our first guide here on this site. Please note that comments are enabled on the bottom so feel free to comment away. This guide is a how-to jailbreak / unlock and enable multitasking on the iPhone 3G on any firmware upto 4.0 So even if you are already updated to 4.0, you are still good to go. Our guide is made using OSX but it will work on windows the exact same way because we are using the latest version of Redsn0w which came out for osx and windows. We're going to make this as detailed as possible so no one misses a step.

First you are going to have to grab the files needed and put them on your desktop.

1. iPhone 3G 4.0 Firmware

2. redsn0w 0.9.5 beta OSX / Windows

Skip the next 4 steps if you are already on 4.0 firmware

1. Next you will have to make sure your iTunes 9.2 or you will not be able to update to 4.0. So go ahead an update your iTunes to 9.2

2. Now we have to update your iPhone 3G to 4.0, let iTunes go ahead and update your iPhone.

3. If you get errors updating your iPhone it's most likely due to because you were jailbroken previously using SpiritJB. In that case put your phone into DFU mode and then restore your iPhone. When clicking the restore button hold down the Option key on the keyboard this will allow you to browse for the firmware. Select 4.0 and then your iPhone will restore.

note : A known bug in OS X 10.6.5 can cause Macs to not detect an iPhone in DFU (recovery) mode. If your Mac is using this OS, then this process may not work. Try the same process on another Mac, or even a PC to avoid this bug. Some individuals do have luck using a USB hub (powered or not) in between the iPhone in DFU (recovery) mode and the Mac with OS X 10.6.5, so if you have a USB hub lying around, this is worth a shot.

4. When the update is complete let iTunes restore your phone so you can get your settings back.

Now lets jailbreak the sucker.

1. Start Redsn0w

Click browse and select the 4.0 firmware from the Desktop.

redsn0w will process your file and you should get a IPSW successfully identified on the screen. Click Next

Here you will have your redsn0w options. If you want to be jailbroken you need to install Cydia. If you want custom logos you can add them here as well. We also want to enable multitasking, homescreen wallpaper and battery percentage so we select those and click next.

Start iTunes if its not running. Turn off your iPhone, the click Next. Redsn0w is going to ask you to put your iPhone into DFU mode, follow the onscreen instructions and put in into DFU mode. You will know when the phone is in DFU mode because redsn0w will continue to the next screen.

Give it a few minutes and your iPhone will reboot. You are now Jailbroken.

Click here for guide to unlock the iPhone 3G on 4.0 firmware