I agree -- everything seemed to go very smoothly, unlike past launches, and that is great! I suspect that having had the deliveries to people who had preordered going out a day or two earlier than originally scheduled made a difference. Also, Apple has clearly learned from previous launches, too, as far as getting other updates/changes, etc., done prior to the launching of a new product. This year we saw the update to OS X, the update to iTunes, the availability of iOS 4 and the changes to MobileMe take place PRIOR to the arrival of the iPhone 4. This definitely eased the process yesterday, too!
Also, yesterday's experience in the Apple store went much more smoothly and felt less chaotic than previous launches, and IMHO that, too, made a difference. Instead of a whole lot of people all in the store at once and sales personnel trying to ring up their purchases and activate their new iPhones all at the same time there were fewer customers in the store at any given moment and each person was being assisted by an Apple person assigned to him or her. That worked very well, too.