It’s a simple economic model, supply and demand. When demand is high, it’s hard to create an adequate supply. For a prime example, see the Nintendo Wii, which somehow is still largely unavailable on U.S. store shelves, despite the fact that it’s been on the market for nearly five months. The iPhone is set to debut to even larger demand, so it’s no shocker that some are predicting that massive product shortages will greet iPhone fans at launch. The problem, however, might be more serious that initially suspected: the generally reliable Ars Technica cites an inside source who reports that “Apple had 50 OS engineers working around the clock in Taipei to make sure that this shipped on time. The issue with the iPhone is not the battery, but the software Q/A and OS-related issues.” Well, that explains the Leopard delay quite nicely but opens up a new Pandora’s Box: if Apple hasn’t started manufacturing the device yet due to these last minute issues, how will they ever produce enough units in time? Again, Ars‘s source has the answer: “It is doubtful they will have enough units on hand to meet the demand.”

For more on the likely shortage:
– see this Ars Technica article