there is a simple way to update to iOS 4.3 without basebande update with Pwnagetool 4.3 or Sn0wbreeze 2.3b4 . easy unlock and jailbreak But its need you have 05.13.04 bb or below. Its a tethered jailbreak for iPhone 4 and iPhone 3Gs new bootrom but it is UNTETHERED jailberak for iPhone 3Gs old Bootrom.
We’ve just been given some info on Apple’s next iOS release, 4.3.1, and from what we have been told, it will contain minor bug fixes. Here are the changes from iOS 4.3: