If you haven't seen a touchscreen iPhone or an iPad, you should go to a store near you and get a demo. In my view it's the biggest paradigm shift since the GUI. If you are viewing this through a normal GUI window (MS or Linux or whatever), it would be hard to explain. First, there is no real keyboard. It is the reason why Google now has a small keyboard in it's search bar. Second it's flat or nearly flat on the table in front of you, like a book. It has no mouse, instead it has all sorts of 'gesture' programming, which means you can scroll by strocking the screen in the direction you want it to scroll. It also has 'kinetic' scroll. Which means it continues to scroll with a gradually damped effect after you finished touching the screen. When it reaches the point you want you just touch the screen again.
pj is right, pm needs to reflect these new changes in technology. They require interface changes.