Roger Clark has a technical write-up on digital camera pixels and pixel pitch, and why we should care.
"In today's Digital Camera market there is a bewildering array of models to choose from. I recently faced such a decision when I wanted to buy a small point and shoot digital camera. I wanted a small size, high megapixel count, fast response time (low shutter lag), and low noise camera. I did not get what I wanted because it did not exist at the time of my purchase. After a little research, I find I never will get what I wanted, unless someone comes up with a way to break the laws of physics.
The sensor in today's digital cameras uses a charge-coupled device, CMOS sensor or other similar device that is an array of pixels. Each pixel, is a semiconductor material that converts a photon into an electron. The electron is gathered and held in what is called a potential well, or voltage well that prevents the electron from drifting away."
Obviously, this artcile gets a little heavy on the physics and math side which is ok for some of us, but it's not for everyone. Happy reading!