MuscleNerd has brought to our attention that Apple is no longer signing the iOS 4.3.3 firmware. Meaning if you did not save your iOS 4.3.3 SHSH blobs you will no longer be able to downgrade your iDevice to the iOS 4.3.3 firmware. Additionally if you have a Wifi + 3G iPad 2 you will be no longer able to downgrade to the iOS 4.3.3 firmware even if you have saved SHSH blobs.
If you are looking to downgrade to the iOS 4.3.3 firmware you can download it, or any other firmware version, through the iJailbreak Downloads Section. Additionally if you are stuck on the iOS 4.3.4 firmware you can still Jailbreak it tethered using RedSn0w 0.9.8b3 (except the iPad 2 unfortunately).