Options for the new machines will include Apple's new wireless-networking technology, Airport Extreme, which supports speeds of 54 megabits per second and is also backward-compatible with standard Wi-Fi gear.
While both Opteron and Itanium ran newer 64-bit software, AMD's chip was also backward-compatible, enabling it to run software written for older 32-bit processors.
And all of a sudden your relatively old refrigerator or air conditioner doesn't work because the new operating system isn't backward-compatible with the systems in these devices.