Bill Gates is roughly 50 billion times richer than me; so maybe he’s 50 billion times smarter, too. But I can’t help wondering if his crystal ball is any less murky than mine, especially when I see him rhapsodizing about the tablet PC. For some reason, he loves to do this in Tokyo: at a news conference (see “Gates Still Roots for Tablet PCs“) in June, 2005, he acknowledged that tablets were “not yet in the mainstream,” but went on to say, “I totally believe in the tablet.” And on April 21, 2006, he showed up in Tokyo again to proclaim “we see a day where every student, instead of their textbooks, will simply have their tablet computer connected up to the wireless Internet.” (See “Gates Sees a Tablet PC for Every Student.”) And reporters love to remind everyone that at a 2001 Comdex conference, Gates proclaimed that “It’s a PC that is virtually without limits and within five years I predict it will be the most popular form of PC sold in America.”

Well, five years have come and gone, give or take a few months, and tablet PC’s haven’t even reached mainstream status, let alone becoming “the most popular form of PC sold in America.” Roughly 640,000 units were sold in 2004, and approximately 1.2 million units shipped in 2005; yes, it’s a nice growth rate, but it’s only about 2% of the worldwide PC market. Meanwhile, ZDNet reports that the PDA industry in Taiwan alone shipped approximately 4.2 million units in the fourth quarter of 2005, and Apple shipped 8.5 million iPods in the first quarter of 2006.

I don’t think the world is breathlessly waiting for a Windows XP-based tablet PC. More importantly, I don’t think the marketplace shares Gates’ vision of the reason we would want such a device: at his most recent Tokyo news conference, Gates opined that, with a tablet PC for every student, “the teacher can customize the material, they can quiz the student. That student can have that tablet with them wherever they go and it’s actually lighter than the textbooks and more flexible, richer in terms of what it can offer.”

The problem here is that the people least likely to anticipate the ultimate use of a new technology tend to be the inventors of that technology. And that doesn’t just mean Bill Gates (to the extent that you want to give him credit for “inventing” anything), or the engineers at Intel, Sony, Samsung, and Toshiba. The phenomenon goes back at least a century: when Thomas Edison invented the phonograph, he presented a “top-10″ list of useful applications to a slightly puzzled marketplace. “Serious” applications like recording the dialogue in business meetings were at the top of Edison’s list; using the phonograph to record music was number 7 on his list. (For a slightly cynical, but thought-provoking, assessment of technology forecasting, check out Bob Seidensticker’s Future Hype: the myths of technology change). In today’s world, the marketplace wants to use these handheld devices to have fun. They want to listen to music, they want to play video games, they want to talk to one another, they want to take pictures of one another, and they want to send instant messages; using the device to do their homework and answer quiz questions is probably not very high on their list.

Though it’s excruciatingly difficult to forecast society’s reaction to, and acceptance of, new technologies, the one thing we can predict fairly accurately is the rate at which the technologies themselves will continue to advance. Moore’s Law is alive and well, and Intel (of whom Gordon Moore was a co-founder) is confident that they’ll be able to continue the trend of doubling the number of transistors on a chip at least through the year 2015. So, in very rough terms, we should expect to see computing devices a decade from now that are 32 times smaller, faster, and cheaper. What happens when we can build an iPod small enough to be embedded directly in your ear? What happens when we can embed our cell phone into one of our teeth? What happens when we can embed our Palm Pilot into the frame of our eyeglasses?

By 2015, Bill Gates will probably have retired — so perhaps he doesn’t care. But as noted above, the engineers at Intel and Sony are probably the last ones to know how society will use this kind of technology. If I was in charge of technology forecasting at any one of these companies, I would be forming focus groups of young kids — probably at the junior high school level, perhaps even younger — to see what kind of wild ideas they have about cool new things they want to do with computer-based technology. And I’ll bet the last thing you’d hear from them is a desire to communicate more efficiently with their teachers in school!