It's only when new products are released like the iphone, ipod touch and macbook air, that the stock is unavailable for a couple of weeks or till when steve set's a release date.
When the last macbook and macbook pro was announced, our store had stock within 48 hours and were in australia.
With previous models, if stores still have stock, they usually discount by 8-10% of the new model price. But if rumors are try about more price points this could differ this time