A couple weeks back, I jailbroke my iPhone, so I could finally join the rest of the techno literati while on a carrier besides AT&T. However, this is one of those popular topics that are fraught with websites that just have a ridiculous number of ads on them. Not only that, it's mostly blogs repeating each other, and you get 2nd, 3rd, or maybe 50th hand information. And a lot of them are un-informational--only trying to sell you iPhone jailbreaking services. Didn't know the difference between jailbreaking and unlocking, and could barely find the page.
Because google search fails in this regard, I will recount that Jailbreaking is when you break the iPhone free of the app store, and you can install software from other sources and app installers, like Cydia. Unlocking is making your phone work with any phone carrier.
Surprisingly, these links were hard to fine--of the actual iPhone Dev Team Portal and of their forum. Those are what I found to be most helpful, though they don't even have a download page, which makes me kinda mad as I hunted around for it. Checkout yellowsn0w, as well as their QuickPwn, also here (much better than Z-phone). If you're still confused, which rightfully, you are. Over at iClarified, there are very good and clear tutorials on how to use the applications.
IPhone unlocking is one of those searches that I think Google just fails at. I hadn't noticed because most of what I search for is usually academic, mathematic, or open source developer related. Those two have been rather blissfully free of intrusive ads of non-informational webpages. With such a system, people know they're being watched and indexed, and if it's an advantage to get a 'high score', they're going to try to game (or optimize) on it. It seems uncannily related to sexual selection. I'll talk about that in another post in the future. For now, enjoy the iPhone resources