iPhone 3G S launch day update:

AT&T is very organized with their pre-order customers at the AT&T store. The store manager has a list of customer names and each iPhone 3G S is shipped in an individual brown box with pre-order customer's name marked on the box.

If you are just buying the iPhone 3G S while keeping the same number and syncing content from the iTunes on your own, the process is quite fast. The AT&T sales rep. will just active your phone number and off you go.