How To Jailbreak iOS 4.3.1 Untethered With PwnageTool 4.3 UNLOCK [Guide]

The just released PwnageTool 4.3 can jailbreak iOS 4.3.1 on iPhone 4, 3GS, iPad (1st-gen), iPod touch 4G/3G, Apple TV, and at the same time will help retain the old baseband for iPhone 4 and 3GS users so that they can unlock using the existing version of Ultrasn0w.
If your iPhone doesn’t rely on a carrier unlock, you can use Redsn0w for both Windows and Mac to easily jailbreak your device on iOS 4.3.1. Complete step by step instructions can be found here.
Unlike the last release, this version of PwnageTool brings full untethered iOS 4.3.1 jailbreak for all devices except for the iPad 2. This untethered jailbreak for iOS 4.3.1 is based on an exploit found by iPhone security expert and hacker Stefan Esser, who demoed it on his iPod touch last week before handing it over to the Dev-Team to do the rest.
iOS 4.3.1 was originally jailbroken last week using PwnageTool bundles (on Mac) and Sn0wbreeze (on Windows) but it was limited to tethered boot.

Step 1: Download PwnageTool 4.3 for Mac.
Step 2: Download iOS 4.3.1 firmware. Move all these files to the desktop.
Step 3: Start PwnageTool in “Expert mode” and select your device:

Step 4: Browse for iOS 4.3.1 firmware for your device as shown in the screenshot below:

Step 5: Now select “Build” to start creating custom 4.3.1 firmware file:

 Step 6: PwnageTool will now create the custom .ipsw file for your iPhone, iPad or iPod touch which will be jailbroken.

Step 7: Now follow the following steps to enter DFU mode using PwnageTool:

• Hold Power and Home buttons for 10 seconds
• Now release the Power button but continue holding the Home button for 10 more seconds
• You device should now be in DFU mode 

 Step 8: Start iTunes, click on your iOS device icon from the sidebar in iTunes. Now press and hold left “alt” (option) button on Mac, or Left “Shift” button if you are on Windows on the keyboard and then click on “Restore” (Not “Update” or “Check for Update”) button in the iTunes and then release this button.
This will make iTunes prompt you to select the location for your custom firmware 4.3.1 file. Select the required custom .ipsw file that you created above, and click on “Open”.

Step 9: Now sit back and enjoy as iTunes does the rest for you. This will involve a series of automated steps. Be patient at this stage and don’t do anything silly. Just wait while iTunes installs the new firmware 4.3.1 on your iOS device. Your iOS device screen at this point will be showing a progress bar indicating installation progress. After the installation is done, your iOS device will be jailbroken on iOS 4.3.1.

How-To Unlock iOS 4.3.1:
Ultrasn0w 1.2 is broken on iOS 4.3.1. Wait for the Dev-Team to push new version of Ultrasn0w to unlock your iPhone (compatible basebands: 01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00).