I recently read on IGN.com that PS3 pre-orders are sold. If you read the article it is interesting to note how few of the units will be available at launch. They state that a typical EBGames store will get less than 20 units. The other interesting point is that you cannot specify which machine you want when you pre-order. So you may end up with the high-end version or the low-end and it is unclear which will appear. It sounds like there will be a continued shortage of the PS3 throughout the fall.
This reminds me of the XBox360 launch (though I think that more 360's were shipped at launch) with demand exceeding supply for the systems for a number of months. In fact there were entire sites dedicated providing information about stores with the XBox360 in stock. Retailers were also forcing buyers to purchase more expensive system packages to generate more revenue. This suggestion lasted until around June of 2006 when the supply situation finally corrected itself. I bet that we will see the same situation with the PS3, and am curious to see how it long it takes for the situation to be corrected.