I don't think 4s is a good indicator of what will happen this Friday. Ipad 3 launch day is a much better preview of what will happen on this Friday. Tim Cook has a very different philosophy in running the retail operations and launching product. He overstock the store with launch products and have enough associate to help the customer. So Apple end up with a lot more sales in the first day and more happy customers too.
Once we get through the morning rush, one should be able to walk into any Apple store and pick up your phone. There may be some model that sold out but they should be able to get it the next day. The delivery system to the store seems to improve a lot and Apple was able to deliver the sold out model to the store. Check out the Ipad 3 launch days experience in the forum. ATT & Verizon of the world are in a tough spot in gauging the demand. They have to put in the first day order to Apple a long time ago. If they guess wrong, they will end up with a lot of inventory to store and move later on. So it is to ATT, Verizon and Sprint's interest to just order enough.. And looks like they guess wrong this time and has to wait for the next delivery from Apple before they can fill some of the pre-order.