I wasn't going to post this - it's a freakin phone after all. But I've gotten quite a few tips on it, and I'd like them to end. [George] made a concerted effort to hack the iPhone - and it paid off. After his crazy ebay auction that topped out at 99,999,999.99 last time I checked, he ended up trading his first phone for a Nissan 350z and a few more iPhones.
He documented his process, step by step - if you've got the skills, you can probably do it yourself. The soldering work is damn fine work - probably the hardest thing there is. The write up is a little hard to follow, so plan on taking some time to comprehend everything. (Blogging software isn't the best way to organize how-tos, trust me on this.) My hats off to [George], he did some great work. - So, why didn't I want to post it? All this work yielded one thing: carrier choice for the iPhone.
http://www.hackaday.com/2007/08/26/free-your-iphone/