RedSn0w 0.9.6 RC 9 iOS 4.3.1 untethered jailbreak is available for Windows and Mac users which could be downloaded through links below.
Download RedSn0w 0.9.6 RC 9 for Windows
Download RedSn0w 0.9.6 RC 9 for Mac
Download iOS 4.3.1
Download iTunes 10.2.1