I think this user input method will be implemented heavily soon, and for ALL apps and all types of users. The reason that it will only be practical for a small group at first is because right now everything is, by design, geared towards the mouse/keyboard/display configuration. It's a gradual process, but once it's recognized that this kind of technology is quicker and more intuitive than the current standard, manufacturers, and most importantly, developers will GET BEHIND it. That's all it will take to make it practical for widespread use.
Go back 30 years. From what I gather, the graphic user interface was invented by Xerox employees, but was laughed off the boardroom table by the company executives. This is because it had absolutely no use at the time - no established, usable apps that worked with it - just like multi-touch now. But then, Apple took that idea (stole it with permission) and turned it basically into what we use on all computers today. I can imagine it would have been a long, laborious, and RISKY process to develop, launch, and get industry support for a computer system based on this brand new GUI concept, but it turned out to be much more efficient and useful to lots more people than a blinking cursor. I think multi-touch is going to be the next logical step in UI, it's just that like any innovation that is intended for such widespread use, it will take time for everyone involved to jump on the wagon, and it will have to happen in a very transitional fashion - not a big jump. It will also take some cajones on the part of those who first implement it in a big way - perhaps this is Apple and the iPhone, or perhaps it will be someone else.
If the iPhone runs a slimmed down version of 10.5 than multitouch could well be inside 10.5... and making a tablet or even a laptop with touchscreen much more interesting then any other available equivalent. and yes, Piles would work very well with multitouch.
I think thats an interesting comment - why not! Another thing that interests me on that note is the question of why Apple allowed Axiotron to make the
Modbook. Could it be so that they have a testing device to work with while still in sandbox mode? I'm not counting on any serious touch screen implementation in 10.5, but hell, the iPhone shocked me, and the technology exists....why not?