So after lurking here for the past few nights, I've decided to create an account just to share what I've found.
I'm in San Diego and I have been calling and checking everywhere for an iPhone 5 64gb black for ATT since its launch.
Today when I decided to check out some stores, I was informed that once they get a shipment in, they will announce to the floor that they have it in stock. The ones that popup in the inventory system after 10pm are from shipments that arrive after-hours, meaning they do not hold the iPhones for this online system.
They also said that they barely get any ATT shipments. They are talking in terms of single digit numbers (3-4 phones) so they are bought as soon as they hit the floor.
I've been checking SD, LA, SJ and SF area each night online while madly refreshing. So far I have only seen the 64gb black available at the Valley Fair store, and the Hillsdale store. The VF one had it up for about 30 seconds before it was gone while the Hillsdale store had it for a good 15+ minutes.
other random info: after calling non-apple stores, it would appear that there are plenty of Sprint phones available so you guys on Sprint are in luck. As for SD area, it would appear that almost all the available phone's I've found were white.
tl;dr: They don't hold any phones for this online system. All the phones that show up on the online inventory checker are phones that came in after hours. Also, the 64gb black ATT phone is near impossible to find in California.