The very back of the queue was initially unmonitored and didn't have the crowd control fences. Eventually the apple staff noticed people getting tetchy and redistributed the security.
Sadly this is most of the reason launch day queuing has lost its appeal. The iPhone 4 launch queue was mostly enthusiasts you could chat and yammer with over coffee & doughnuts supplied by Apple. Now it seems to be scalpers and scammers agressively queue jumping; alas Apple store staff can only exert so much control over the queue and the behaviour of people in it.
Even as far back as 2003 I was queueing from 4 in the morning for Paul McMcartney tickets in Manchester and the couple of hundred people in front of me were self evidently there to aquire tickets for flipping on ebay. Perhaps as the smartphone & tablet market continue to mature, the day 1 resale value of these things will drop off to the point that it will only be really worthwhile to to the tech/Apple enthusiasts to do. /SheerOptimism