A very nice article by Bob Atkins at Photo.Net which shows that the current obsessive focus on simple pixel count to judge digital camera quality is not as useful as people think.
His point is that the correlation between sensor size and the lens used is also a very important factor to take into account when choosing a digicam. He compares three 3 megapixel cameras (Nikon, Canon and Minolta) to provide an example. Worth reading if you’re in the market for a digicam.
I would also go further than this, and say that factors like the file compression method used, the lens quality and the in-built photo processing firmware (which determine, inter alia, things like the colour balance your camera gives etc) are just as vital in determining the overall camera quality.
I’ve tested a few cheap Far Eastern digital cameras recently, with 2 or 3 megapixel ratings, and the results they give have been pitiful compared to a decent brand name digicam. That’s why it’s vital to try and test a camera before you buy, and especially if you can get a look at the quality of the printout.