I turned up at 6am for the iPhone 4 launch and if I'd arrived 20 minutes later I wouldn't have got one
Having said that I can't see the 4S launch being as busy for O2. Firstly it's only a minor update from the 4 so not everyone will bother. And secondly O2 are losing customers left right and centre over their decisions to not offer pre orders and to bar fast track upgrades for all but the highest spenders