You may be the first in line to wait overnight, but you may not be the first person to buy the iPhone at this Apple Store.
I camped for the iPad launch and they split the lines in two a few hours before store opening. Folks with reservations got to go in first. For every ten people with a reservation they only let one in without a reservation.
Still a really fun experience meeting fellow enthusiasts and you may get your mug on CNN, NYTimes, Reuters, AP, random world newspapers. :P I was lucky enough to be the first to walk out w/ an iPad at SF Apple store even though I was third in the reserved line.