Earlier today, Sn0wbreeze 2.5.1 for Windows was released to jailbreak iOS 4.3.1 untethered on iPhone, iPad and iPod touch. Sn0wbreeze 2.5.1 brought a host of bug fixes, Cydia 1.1.1 pre-installed and support for Animate - custom animated boot logo for iDevices. Redsn0w for iOS 4.3.1 untethered jailbreak was also updated to Redsn0w 0.9.6rc11 which also brought the ability to enable animate on iDevices. This guide will tell you how to enable animate on your iOS 4.3.1 untethered jailbroken iPhone, iPad and iPod touch.

Step 1: Jailbreak your iDevice using Sn0wbreeze or Redsn0w
If you're jailbreaking iOS 4.3.1 untethered using redsn0w, simply check "Enable boot animation" and you'll be good to go. Also, please keep in mind that if you have previously jailbroken your device, uncheck "Install cydia" for avoiding package conflicts.

If you are jailbreaking iOS 4.3.1 untethered using Sn0wbreeze, after the ipsw file is verified, proceed to Expert Mode followed by General. There, check "Enable Animated Logo Capability" and that should be enough.

Step 2: When you've sucessfully jailbroken your device, all you need to do now is to load Cydia and install "Apple Boot Logo" Once installation completes, restart or respring your device, and it will now have custom animated boot logo.

Step 3: Now, just search Cydia for whatever theme fancies you. By searching for "BootLogo," Cydia will show you many themes which can now be activated through the new BootLogo menu in Settings.app.
If you face any difficulties during the procedure, let us know and we'll be glad to help you out.
Important Links:
Download iOS 4.3.1 for iPhone, iPad and iPod touch
Download iTunes 10.2.1