The iPad revolutionizes the whole notion of techno gadgetry! Yet, when I think about it, this is another case of people catching up with technology. Touch-screen technology has been around for more than a decade, with only a few applications gaining any measureable traction. The fact of the matter is, only a few could mentally bridge the user interface. I posit that a generation of young people growing up with handheld games provided an "experienced" population that could kickstart the trend to the micro-user interface. Next, the advent of the cell phone and texting broadened the base and gave rise to innovation in trying to address those shortcomings.
One shortcoming is everyone who simply has to have a qwerty keyboard. RIM has made a niche market of those who cannot make the texty shift to 10 keys, but the market analysts show that the need for this crutch is falling off fairly rapidly. I say "good." In 20 years, we might finally be rid of the only known technological innovation specifically designed to cripple the user (the qwerty keyboard was designed to slow typists down in the days of mechanical typewriters). On the other hand, I found the onscreen keyboard too alien for blogging or any activity with a lot of input, so I bought the bluetooth keyboard, too.
Insofar as the other required technologies giving rise to the iPad; I have seen it blogged that the current generation of small, low-power devices are a direct result of the efforts put into the Open Source OLPC (One Laptop Per Child) project. Lighter, cheaper battery technology, low power consumption (doesn't the OLPC have a wind-up mechanism?) and a return to not-bloated software, if that's a real phrase.
Have you noticed that the iPad is sort of the domain of the young and the old? At the office, the big users are mostly past 50, with a few younger users. If younger women have them, they're not telling, but the young men all have Droids or iPhones. Middlin' young folks from 13 to 30 are doing very well with their touch screen phones, thank you. After a fashion, they have leapfrogged the touchpad revolution and are already in the middle of The Next Big Thing. the iPad is just there so that the rest of us can catch up. I know that I am having fun with mine!