Step by Step Guide for Jailbreaking:
Step 1: Download the latest iTunes 9.2 which supports iOS 4.
Step 2: Download the public release iOS 4 for your iPhone and place on your desktop for quick access.
Step 4: Run the snowbreeze.
Step 5: Click Next.
Step 6: Select the Export Mode if you want to enable the multitasking and background on iPhone 3G. Multitasking is disabled by default in iOS 4 for iPhone 3G. Click Next.
Step 7: Click browse and select the iOS 4 firmware which you downloaded for your iPhone 3G/3GS.
Step 8: If the firmware is correct, you will see a confirmation message. Click next.
Step 9: Now you will see different option. Select the General.
Step 10: If you have iPhone 3G, select multitasking and background wallpapers if you want to enable them. It is to be noted Background Wallpapers and Multitasking features might slow down your iPhone 3G. If you have got iPhone 3GS, don’t select any option because they are enable by default.
Step 11: Let the snowbreeze work. After processing you will get the confirmation that the custom firmware has been created. The custom firmware will contain the word “snowbreeze” before the file name.
Step 12: Now connect your iPhone 3G/3GS with the PC via iTunes 9.2. While holding the SHIFT key, click restore button. It will ask for firmware file which you have created at Step 11.
Step 13: Now sit back and let the iTunes finish the restore process.
Step 14: Now your iPhone 3G/3GS is jailbroken. To unlock these phones on iOS 4, read our guide for Ultrasn0w 0.93.