Redsn0w 0.9.6 iOS 4.3.1 jailbreak is released with a slightest of update that claims to rectify any of the issues related to the boot animation.
However, you can also opt for Sn0wbreeze 2.5.1 for Windows to enable the custom animated boot logos on your iDevices such as iPhone, iPad and iPod Touch.
The procedure for jailbreaking iOS 4.3.1 untethered for both latest and last version are almost the same. What you need to do is to download Redsn0w 0.9.6rc12 for Windows or Mac and jailbreak your iPhone 4, 3GS, iPod Touch 4G/3G and iPad that are based on latest iOS 4.3.1 firmware.
If you have your device already jailbroken on iOS 4.3.1with Redsn0w 0.9.6rc9, rc10 or rc11, you just need to re-run the Redsn0w 0.9.6rc12 on your current jailbroken device by choosing ‘Allow boot animation’. Before selecting the option, make certain that the option ‘Install Cydia’ is unchecked so that no package conflict with the current jailbreak arise.
Once you are done with it, you can follow the step by step guide here to install ‘Apple Boot Logo’ also known as Animate.
It is important for those who rely on carrier unlock should stay away from Redsn0w and stock iOS 4.3.1 firmware.
Download Redsn0w 0.9.6rc12 for Windows
Download Redsn0w 0.9.6rc12 for Mac
Download iOS 4.3.1 for iPhone 4, 3GS, 3G, iPad, iPod touch
Download iTunes 10.2.1 for Windows or Mac
via RedmondPie