After a weekend of great sales of the new iPhone 4S, Apple has now updated their “how to buy” page, and now notes that Apple retail stores in the US and Canada are now selling the device on a reservation-only basis.
This means customers looking to buy the device will have to visit the Apple online store after 9PM (presumably local time) to reserve their device for in-store pickup the next day. This is likely due to the strong sales, and the quickly diminishing supply of the device.
Other countries are also seeing sales restrictions. For example on-contract customers are the only customers allowed to make walk-in purchases of the iPhone 4S, with contract-free customers having to make reservations. Presumably this would be to cut down on scalping.
That said, Apple likely will not refuse to sell the device to walk-in customers, but as supplies grow ever-tighter as we move closer to the holiday shipping season, Apple may begin to direct their customers towards making reservations for the purchase of their shiny new iPhone 4S.