One of the coolest new technologies to come out of RIM lately has been the introduction of the trackpad. Gone are the days of faulty trackballs or cleaning the "finger dirt" out by popping off the trackball assembly. Yeah, the trackpad is cool. But how does it work? The simplest explanation would be to compare it to an optical mouse. But instead of a desk, the trackpad uses your finger.
David (Vice President of Handheld Products) says to imagine it as "an infared video camera turned upside down.". It basically just takes a picture of your finger as it passes over the pad. This gets translated into movement. Possibly the most intriguing thing about the trackpad is that you can use nearly anything that has a rough surface. Since it does not require any conductivity (such as a touchscreen) items like pens, paper or pencil erasers could be used instead of a thumb or finger.