Geohot has just released limera1n for Mac to jailbreak iPhone 3GS, iPhone 4,  iPad, iPod Touch 3G  and the new iPod Touch 4G.

This guide will provide you step-by-step instructions to jailbreak iPhone 4 and iPhone 3GS using limera1n.

Here are some important points to note before you proceed.

• This guide is only for iPhone 4 and iPhone 3GS users.

• Please note that jailbreaking your iPhone may void your warranty and hence proceed with caution.

• Do not forget to backup your iPhone before you proceed. You can refer to this post for instructions on how to backup your iPhone.

• Limera1n supports iOS 4, iOS 4.0.1, iOS 4.0.2 and iOS 4.1.

• This guide is only for Mac users. Windows users can checkout our step-by-step guides to:

  • Jailbreak iPhone 4 and iPhone 3GS using limera1n

  • Jailbreak iPod Touch 3G and iPod Touch 4G using limera1n

  • Jailbreak iPad using limera1n

• Please do NOT upgrade to iOS 4.1 if you want to unlock your iPhone. iPhone 4 users can use Tiny Umbrella if they want to upgrade to iOS 4.1 to preserve the baseband so that they can unlock it using Ultrasn0w after jailbreaking their iPhone. iPhone 3GS users should wait for iPhone Dev Team to release PwnageTool.

• Limera1n does NOT hactivate your iPhone, so your iPhone should be activated via iTunes first.

• After the jailbreaking process is complete, do not forget to checkout our article on tips to keep your iPhone secure.

• Please ensure you are running iTunes 9.2 or later.

Step 1: Download the latest version of limera1n for Mac from this link and save the application on your desktop (click on the Mac logo).

Step 2: Double click on the limera1n.zip file to extract it and then double click it to launch the application.

Step 3: Please ensure that your iPhone is connected to the Mac.

Step 4: Click on the "make it rain” button.

Step 5: You will see that limera1n puts your iPhone in recovery mode. Immediately after this, follow the instructions.

Step 6: Limera1n will be prompt you to press both the home and power buttons.

Step 7: Limera1n will be then prompt you to release the Power button. Continue to press the home button.

Step 8: You will see that limera1n has put your iPhone in DFU mode. Continue to press the home button.

Step 9: While limera1n performs the exploit, you will see the limera1n logo on your iPhone. At this point it is fine to release the home button.

Step 10: When limera1n has successfully jailbroken your iPhone, you will see “done” and get the following message.

Step 11: You need to restart your iPhone. You will notice that there is a new app called limera1n installed on your iPhone.

Step 12: Launch the limera1n app to install Cydia on your iPhone. Select Cydia and tap on the Install button to download and install it.

Step 13: After Cydia has been installed, it will automatically reboot your iPhone.

Step 14: You should find Cydia on your iPhone’s homescreen after its rebooted. You can launch the limera1n app to uninstall it as it is no longer required.

Hope this helped. Please don't forget to drop us a line to tell us how it goes.