Chỉ áp dụng có 3gs old boot và không jailbreak bằng spirit lúc trước.
While waiting for iOS 4.1 jailbreak release (may be SHAtter?), we will give a guide to jailbreak iPhone 3GS old bootrom only on iOS 4.1 using a modified version PwnageTool from Criminal90 with the help of some other tools which is essential in the jailbreak process.

This guide requires iPhone 3GS old bootrom on 3.1.2 (jailbroken with Blackra1n) or on 3.1.3 (jailbroken with Sn0wbreeze / Pwnagetool not with Spirit). If you have SHSH blobs of 3.1.2 or 3.1.2, use our guide posted here to downgrade, then jailbreak your device and follow the step by step guide below.

Note: Do it on your own RISK, we are not responsible for any damage happens to your device.

Step 1: Download the required files,

• Download iOS 4.1 firmware and save it on your desktop,
  
• Download iTunes 10 and install it,
  
• Download the modified PwnageTool and iOS 4.1 Jailbreaker
  

Step 2: Launch PwnageTool and connect your iPhone via USB, you should be promoted with a warning message, hit OK to start.

Step 3: Click on Expert Mode button, select iPhone 3GS, then hit the blue arrow.

Step 4: You will be brought to the "Browse for IPSW" page. click on Browse for IPSW and point it to iOS 4.1 you already downloaded above.

Step 5: Now click on "General" to begin the customization,

• Deselect Activate if you have an iPhone legitimately activated on an official carrier.
  
• Adjust the partition size as you want, or leave it as it's.
  

Step 6: [Optional] After you end customizations, hit the blue arrow. Now you are in "Cydia" page, through this page you can add repos in Cydia and install applications as you want.

Enter "Manage Sources" section to add repos, then select the "Download packages" tab and click the Refresh button to display all the available packages. Double clicking the package you want will download it and make it available in the "Select Packages" tab. Make sure that everything is fine and hit the blue arrow.

Step 7: In this page, you can uncheck both Boot logo and Recovery logo to keep default Apple's logos or click on "Browse" to replace them with another image then hit the blue arrow.

Step 8: Now the Pwnage process will start, select "Build" button to start building your custom firmware. You will be asked to locate the place to save the custom firmware, select anywhere (i.e. desktop) and hit "Save". Building the firmware process will start.

Step 9: The process will take up to 10 minutes. While creating the custom firmware you will be asked to write your system password, DON'T write it! Instead, install iOS4.1Jailbreaker installer package (downloaded above with PwnageTool) and hit "Continue" twice and write the admin password if required.

Step 10: Now switch back to PwnageTool and type in your password. You will get a pop-up that will tell you to put your iPhone in Recovery Mode and restore with iTunes.

Step 11: Now launch iTunes, sync your device. Once in iTunes, hold the Alt / Option key and click Restore. Locate the create ipsw file, click OK and let iTunes extract, verify and restore your iPhone 3GS.

Step 12: Now you have to get out of recovery mode, download TinyUmbrella, launch it and click on "Kick Device out of Recovery Mode"

Step 13: Well done, you have an iPhone 3GS on iOS 4.1 jailbroken and you will find Cydia on your home screen. But you may face this problems:

• If Cydia has a blank icon (no repos) load it go to Manage > Sources > Edit > Add and add http://apt.saurik.com/cydia-3.7
  
• If Safari web browser is crashing, add http://repo.woowiz.net repo and install Safarifix
  

How to: Unlock iPhone 3GS on iOS 4.1:
To do so, you need to be activated on original SIM or Phonebook card. Follow our guide posted here to unlock iPhone 3GS on any baseband using Ultrasn0w 1.0-1.

Now a lot of people still not happy, but the world will be free very soon by the next jailbreak from pod2g with the help of p0sixninja. Just stay tuned and we will keep you updated