The Info:

This guide is pretty much just for the iPhone 3G and the iPhone 2G. The iTouchs should be able to downgrade like normal. The problem with the iPhones is that the baseband is updated when you upgraded to 3.0. iTunes is incapable of downgrading the baseband and realizes that the baseband is not what it should be on 2.2.1, so it gives you a 16xx error. This guide should help you successfully downgrade from 3.0 to 2.2.1.

The Info

Why would you want to uninstall iTunes, especially if you’re on a Mac? Because Apple is constantly trying to prevent jailbreaking. The latest version of the iTunes 8.2 pre-release rewrites the way that your computer communicates to your iPhone over USB, effectively breaking every program that talks to your iPhone over USB. On a PC, its really easy to downgrade iTunes just by uninstalling the current version and installing an older version. On a Mac its not so easy. Thankfully, MuscleNerd figured out how to completely uninstall iTunes on a Mac.