TechCrunch: At midnight Pacific time on Friday morning, Apple.com began taking pre-orders for the iPhone 5. Within one hour, the online store sold out of the units available for delivery on launch day, and the ship date for new orders slipped to two weeks. That's the fastest iPhone pre-order sell-out ever. By comparison, it took 22 hours to sell out pre-orders for the iPhone 4S and 20 hours to sell out the iPhone 4.
If you're still hoping to pre-order an iPhone 5, your best bet may be to try one of the carriers' websites. You can also place an order in person at your local Wal-mart. Otherwise, you might have to wait in line on launch day, September 21.