One not-so-minor detail was left out of today's otherwise laudable iPhone 3G introduction: in the United States, you won't be able to get 3G speeds -- touted as 2.8X faster than 2G speeds -- in many of the areas that are covered by the slower EDGE network.
AT&T says 3G coverage is available in "most major metropolitan areas and is expanding rapidly," but the company refuses to offer a nationwide look at 3G coverage relative to EDGE coverage. Instead, you can view 3G coverage only by selecting specific metro areas.
A poster to HowardForums, zephxii, cobbled together a nationwide map based on AT&T's disparate data, and the picture isn't pretty. While 3G coverage does indeed cover most major metropolitan areas, large swaths of the country and many states are completely excluded from coverage where EDGE access is plentiful. In the image below, blue represents 3G coverage, while bright orange represents EDGE coverage, and lighter orange represents partner coverage.