Good news for the people those are waiting for iOS 4.3.1 untethered jailbreak. Finally iPhone Dev Team has announced the release of much awaited PwnageTool 4.3 for iOS 4.3.1 untethered jailbreak. Using PwnageTool 4.3 you can untether jailbreak iPhone 4, iPhone 3GS, iPad, iPod touch 4G, iPod touch 3G, Apple TV 2G on iOS 4.3.1. You should note that you will not be able to jailbreak your iPad 2.
If are relying on Ultrasn0w carrier unlock then you must stay away because Ultrasn0w is not compatible with iOS 4.3.1. You can download PwnageTool 4.3 for Mac OS X from the link given below.