Apple's official reason behind the Apple TV delay is that "it's taking longer than expected." So what does that mean? The device can't be that hard to make, because all the components are pretty standard. It can't be a shortage of any particular component, because that would have been apparent to Apple months ago.
It might be a software glitch, but again, I think that would have been apparent months ago. What critical steps are missing?
The one that sticks out to me is FCC approval, and that was the subject of the story I wrote on the subject that was published this morning. I don't see any evidence that Apple has gotten Apple TV through the requisite approval process. The thing will have an Airport card in it that's capable of doing 802.11b, g and n, and that would have to be approved by the FCC for home use. I searched the FCC database for Apple products, and the most recent one was the latest Airport Extreme router. I also searched for recent approvals sought by some of Apple's contract manufacturers, including Inventec, who is the one widely thought to have be making AppleTV, and found nothing.
It's an educated guess, I admit, but right now, its best explanation as to why this product is being delayed.