In a sense AAPL answered the question in the negative a while back, when it dropped "Computer" from its corporate name.OTOH isn't iOS an operating system? What else but a computer runs under an operating system?
I guess maybe the "PC" is dying. If you define the "PC" in terms of the traditional keyboard and mouse . . .
Almost everything runs under some kind of OS these days. Embedded Linux and VXWorks are in probably billions of tiny devices, from your GPS and your set top box or DVR, to your wireless router. The days of basic circuitry running electronics devices are waning.
Now that I've thought about this a bit I have to disagree with the author. An iPad cannot be counted as a PC for one reason: it is dependent on a computer for setup and synching. That makes it a satellite device along with PDAs. I'll change my mind when you can pull an iPad out of the box and start using it without first plugging it into a computer.