Well, first of all, the phone only came out Friday, July 11, which was probably your "Just the other day". Then they proceeded to sell greater than 1 million units over the course of the weekend so, yes, they are sold out.
My understanding is that in most cases it would not be worth getting up over the weekend since even if a store happened to get a shipment, they will very likely all be spoken for for at least a few weeks. I was told here in New York that anyone signing up for one on Monday, July 14, would not probably not recieve it for at least a month.
That said, where did you see an availability site? I have been searching since reading your post and can't seem to locate it.