At this point, it seems that third-party application users are good to go on the new firmware, and overseas or non-AT&T iPhone owners are pretty well set for getting unlocked and rolling on native cell networks, noting as always that the hacks are not finished works and even the experienced few sometimes do themselves harm. (Wondering how to tell an unlock from a jailbreak? Check out Erica's iPhone hack glossary post from a while back.)
For those who consider themselves economically and intellectually distanced from the whole unseemly business of hacking iPhones and unlocking them from AT&T's network, consider these two BusinessWeek stories on the iPhone gray market. Not only is the iPhone unlock a money-making engine for thousands of opportunity-minded retailers and middlemen all across the globe, but the status of a functional software unlock means feast or famine (both essentially unwanted) for the maker of the TurboSIM adapter that enables a hardware unlock when software is foiled. It's astonishing that one little device can cause so many ripples in a worldwide chain of commerce and underground innovation.
Thanks to everyone who sent these in.