Jailbreak geniuses have been working on an untethered jailbreak for iOS 4.3.1 for quite some time. It appears that they are now ready, and Redsn0w 0.9.8 and PwnageTool 4.3 will be released today. Redsn0w 0.9.8 will be available for both Windows and Mac users while PwnageTool 4.3 will be compatible with Mac only. All devices running iOS 4.3.1 will be supported by the jailbreak except for the iPad 2.
We will let you know as soon as it comes out.