Gawd, I'd hate to be the AT&T store rep who pulled the short straw and has to answer phones today. Must be a nightmare.
I've ordered a new phone on launch day since the iPhone 4. It's always like this, or pretty much like this. They never have enough phones, the website is always overwhelmed, order status is always wonky, and people are always mad. It's just how it is. The iPhone is hugely popular and they can only make so many at once. They also can't box them up too far ahead of time until the OS is done and can be loaded (which is like a week before release date).
I've learned to let go of the idea that I must have my new phone on launch day. Heck, this year AT&T wouldn't even accept my order until 2 am PST (probably because our account has a FAN discount linked to my wife's employer). I'm quoted 2nd half of October for shipping. I have no idea whether it will ship early, on time, or late. Probably late, but manufacturing might get caught up.
I'd love to have my phone tomorrow, but my later ship date is almost a relief because I know I'm not getting it tomorrow so I have no reason to obsess about it.