I thought this was a great quote from the Anti-Mac article:
"The desktop metaphor assumes we save training time by taking advantage of the time that users have already invested in learning to operate the traditional office with its paper documents and filing cabinets. But the next generation of users will make their learning investments with computers, and it is counterproductive to give them interfaces based on awkward imitations of obsolete technologies."
It reminds me of a recent (non-computer related) incident in my own life. My son's preschool teachers recently had the students in my son's class do an art project where they made phones out of two pieces of construction paper and a piece of yarn. The two pieces of construction paper were cut to look like a old Bell telephone handset and base. I'm sure some of you can see where this is going... the amusing, to me at least, result was that all of the children followed directions and built their project, but couldn't identify what it was. Most of them had never seen telephones with a cord and couldn't figure out how an object too big to fit in your pocket was supposed to be a phone. :-)
I think this illustrates a long term problem with computer interfaces that mimic real world objects and/or interactions, even in the simple case of icons that resemble real-world objects. The real world changes. We haven't had to deal with that much yet, because visual computer user interfaces have only been prevalent so recently. But as time wears on, I think this is only going to get more awkward.
As an example related to my story above, both the iPhone UI and the Android UI use an icon that looks like an old Bell telephone handset to represent the dialer. That image still makes sense to my generation, but IMHO to my kids it's just gonna look like a wierd abstract symbol. Similarly, many applications use an icon that looks like a Rolodex to represent the "phonebook" application. Heck, I think I've got co-workers who've never seen a Rolodex!.