Originally posted by Somebody
Doing updates every 6 months mean that there are these large, sharp drops in the price associated with a given level of performance. Meanwhile, the value of a specific computer in a user's hands drops in a smoother, less jerky fashion, because, while it's influenced by the drops in price/performance that come with machine updates, people to some extent anticipate those drops.
Because of this, informed buyers tend to wait until just after new releases to make their purchases: That's the point at which the difference between what the pay for the machine and the value it will have when they receive it will be the lowest. So Apple goes from having fairly low sales on a model to suddenly having a huge number of orders to fulfill, in a short period. People like tedkolb get angry because they feel ripped off, and people like me are frustrated because we have to wait a long time for our lovely new machines to arrive.