The iPhone 5 went on pre-order at 12:01am PDT on the Apple Store App. The online store went online about 50 minutes later. Now the Apple Store iPhone 5 product pages already reflect a 2 week shipping time frame. Initially it said September 21. This effective one week delay is shown in the US Apple Store as well as on the European Apple Stores.
The demand for the iPhone 5 was predicted to be really high. It might be even crazy high if Apple had produced a significant amount of iPhone 5 devices in the first wave.
I entered my iPhone 5 pre-order on the German Apple Store, just when the Apple Store went online. My order confirmation already reads: ready for shipment: 2 weeks. Apple is usually ever pessimistic with shipping estimates. So I hope things still change and I receive the iPhone 5 on release day or shortly after.