The iPhone 3G isn't for everyone, at least not on the first day. If you had the insight to camp outside of an Apple or ATT store a day before, you look very smart now. But if you got to the line today, you will likely be stuck in a long, long lines.
We dropped by several AT&T stores around Dallas area, the lines were long and had only limited supplies and have sold out most of their stock by mid-morning. The Apple stores here'd have more phones in stock but the wait is about 6 hours thanks the incredible slow and some time not working activaction system. At least they are feeding people free pizza and providing water, coffee and lemonade.
It seems that neither AT&T nor Apple had anticipated the level of high demand of the 3G iPhone. The Apple store staff is telling the customer waiting in line that their stores will continue to receive shipments everyday except Sunday. So if you don't have 6 hours to stand in line today, wait until Sat. Or next week.