This is the first time I plan on buying an iPhone without preordering it first. So, my question is, if I were to go to an AT&T store at opening (or even wait outside beforehand), would there be iPhones available for customers who haven't preordered? A colleague of mine mentioned that for the 4s, customers that waited outside were given "tickets" once the store opened that allowed them to purchase it that day at their convenience. What should I expect on launch day at an AT&T store? Is the supply usually good enough to walk in as soon as they open?