With a Good Better Best system, the best technology will start at the top end and gradually trickle down through the rest of the line. For instance, the DVD-RAM drive was on the Best model this year, and would be on the Better model next year, and on the Good model the year after that. CHECK THIS
Shortly after the launch of the PowerMac G4, Apple was forced to go in the other direction, bubbling inferior technology up through the line-up.
The Good Better Best models announced at this keynote were designated by their processor speeds: 400, 450 and 500 MHz. But the processor speeds weren't the only differences. The three models all had different amounts of RAM, size of hard drives, and three different optical drives.
And there was a major difference not really mentioned during the keynote. The cheapest PowerMacs, which went on sale immediately, basically used the old G3's motherboard with PCI graphics. The more expensive PowerMacs would be using a new AGP graphics-based motherboard with lots of new features, the most important of which was the ability to drive the new Apple Cinema Display.
When Motorola called up Apple a few weeks later to say they couldn't make very many 500 MHz G4 chips, Apple was in a quandary. The best model, with the best components and the best margins, had to be on sale this Fall. The only way to sell it would be to put the 450 MHz chip in it. But Motorola wasn't making enough 450 MHz chips to supply both the Better and Best models, so like dominos toppling over, the line-up had to be reconfigured all the way down the line.
Good Better Best was reconfigured to have 350, 400, and 450 MHz chips. Customers were not happy, but there was little Apple could do. As soon as Motorola was able to get the 500 MHz processors out the door, Apple reset the line-up back to the intended one, and announced it at the Macworld Tokyo keynote.
It was a rare (but not sole) case of Apple announcing a product they couldn't ship. If Apple was a purely build-to-order company, and didn't need to stock retail stores with ready-to-go SKUs, this would have been an incredibly minor issue. The 500 MHz option would simply have been greyed out (or not shown) on the Apple online store for six months.