Well online is a for sure way to know that you would get it. Whereas checking your local store to a point where the employees know your name when you enter does get a little weird... and a waste of time.
Just order online, sit back and wait for it to arrive, because it would.
I had to re-order one today due to a screw up with the initial order. Online confirmation says delivers by July 29. I'll keep looking locally and cancel if I happen across a 32GB otherwise it's going to be a long month.
Like the post above me, I recommend ordering from AT&T's website. I ordered on June 30th, it was shipped today, and will (hopefully) be delivered on July 6th. For some reason they are getting some shipments out very quickly.
I'm amazed people are having the issues finding these as they are.
Two local stores here in Orlando still have the 16GB's in stock - or they did as of 7:30pm EST tonight.
Find somebody who lives near an AT&T store that has one, authorize he/she on your account, have them buy the phone, activate it, package it back up and ship it to you...