Just saw this article. What defines something as a portable computer versus a phone, or a tablet? Heck, what qualifies a tablet as a tablet rather than a computer? There are certainly a number that qualify as both.
Endgame of this is, what defines a computer today? A random person on the street would say that the ipad is not a computer, and from a perspective of what I think is generally considered a computer (currently), the ipad is not.
However, the article makes me think; is what we're really reacting to about a computer whether or not it has a mouse and keyboard interface? As one of the commenters in the article noted, mainframe users in the 70's would have scoffed at the notion that a PC was a computer, and likened that comparison to Steve Jobs saying that in a few years desktops/laptops will be like "trucks". They're useful, but most people don't need one.
I think I agree with this argument. The ipad clearly is filling void in the market, if sales are any judge. I can't yet say it's a device that I really need (want is another question...). Talk to me a year (or less!) from now and I may be singing a different tune.
To extend this further, if we're calling (or even considering calling) the ipad a computer, then why not the iphone and other smartphones? You can install software, cruise the internet, do some mild productivity, check the news, and any number of other tasks previously relegated to the computer.
What a computer is has changed, and is still changing. Five years from now I have no idea what kind of form factor I'll be typing a blog post on.
Ten years from now? I probably can't completely conceive what it will look like.
Twenty years from now? I suspect it will be in my head, a coprocessor for the gray matter already there.