Jailbreak & Unlocking an Iphone 3G w/ 2.2.1 FW
How to do this EASILY via software using Mac OS X?
I spent a long time trying to figure this out. Ziphone doesn’t seem to do it (it doesn’t brick the iPhone, it just forces a restore). Some of the others are too hard (SSH’ing to the iPhone, come’on really…script it or something!). Sure, I understand the reason why 2.2 works and 2.2.1 doesn’t for the unlock (the baseband upgrade), and honestly, I don’t care. I just want to be able to click a button and follow some on screen instructions 
My final (working) solution? Don’t. Upgrade to 3.0 and do it with that.
Basically, get a copy of redsn0w to jailbreak the 3G 3.0 firmware and install Cydia, then add the Ultrasn0w repository and install ultrasn0w. Complete! I also did this on an un-activated iPhone by doing the install via Wifi instead of 3G.
Complete instructions for obtaining and installing redsn0w are available at iClarified.
Complete instructions for the jailbreak + unlock technique are available at Quickpwn (obviously, using the instructions above for the jailbreak…it really doesn’t matter how you jailbreak your phone, only that it /is/ jailbroken to enable the Cydia install).