Apple released iOS 4.0 to fix the jailbreakme jailbreak exploit, but the redsn0w exploit for iPhone 3G and iPod touch 2G is still not fixed. The latest release of redsn0w 0.9.5 beta 5 will not only jailbreak your iPhone 3G or iPod touch 2G, but also hactivate it (activate it if it’s not already activated by iTunes). You can also install ultrasn0w at the end via cydia to unlock your iPhone for any carrier.
Download Redsn0w tool :
Windows (link not working: http://sites.google.com/a/iphone-dev.com/files/home/redsn0w_win_0.9.5b5-4.zip ) | Mac OS (link not working: http://sites.google.com/a/iphone-dev.com/files/home/redsn0w_mac_0.9.5b5-4.zip )
Make sure that your iPhone / iPod is upgraded to iOS 4.0.2
Download the files appropriate to your device and operating system.
Connect your iPhone 3G or iPod touch 2G to your computer and launch redsn0w 0.9.5 that we just downloaded.
When redsn0w asks you to select the firmware, browse and select the iOS 4.0 that we downloaded above (not 4.0.2! )
Select the install Cydia option.
In my personal experience enabling multitasking, homescreen wallpaper and battery percentage makes the iPhone 3G get slow and crappy, so I will not recommend selecting those options. Just select install Cydia and that’s it.
Proceed with the instructions on redsn0w. Turn off your iPhone, then follow the steps to enter DFU mode and so on.
Let redsn0w work on your iPhone / iPod touch. It may take 5 to 10 minutes to jailbreak your iPhone 3G / iPod touch 2G.
If you want to unlock your iPhone 3G for carrier install ultrasn0w using cydia on your iPhone.