ComputerWorld has an article about the evolution of Apple’s Trackpads and about the extra features that many users don’t know about:
While almost anyone who has ever used a laptop knows the basics of
using a trackpad as a pointing device (simply drag your finger over its
surface to move the cursor on-screen), not everyone knows about all the
features that Apple has added to its trackpads over the years.
Depending on the Mac notebook model, there are up to 10 specialized
trackpad functions you can use to make navigating the screen, Mac OS X
and various applications faster and easier.
The “secrets” aren’t really that secret — all you need to do is open the system settings to learn about features like tap-to-click and drag lock (and the same goes for touchpad drivers on Windows). But it’s worth remembering that most users, probably well over 90%, never touch their computer’s settings, especially their trackpad/touchpad settings. A problem with touchpads is that they offer no affordances beyond touching. All the other features are hidden away, and that means improved usability may be hidden away as well (a common exception is markings to indicate scroll regions). A simple example of this is tap-to-click. Novice users tend to use the physical buttons for clicking. If they discover tap-to-click it will be accidental (and irritating!). But once they understand how it works and have practiced it most users come to prefer tap-to-click and they also learn how to avoid accidental taps.
Multitouch gestures are hot these days and a welcome side-effect is that this publicity may get more people looking closely at their touchpad settings. Even simple things like tweaking the cursor speed could make a big difference in usability for some people.