I've just had a source kindly let me know that the iPhone 5 is set to go on sale on the 21st of September. Others have also rumoured that this is when the iPhone 5 is set to go on sale.
My source seems pretty certain though, they say they work at BestBuy. They say that no one is allowed to request time off on the day so they can manage the amount of customers which will be coming in. They dug through the computers to find out their projected sales for the day and they says that it is five times what they get on an average day.
I'd be surprised if the iPhone 5 does not go on sale on that day with the amount of rumours flying around specifying the same date.