The Megapixel Myth

Good article on the The Megapixel Myth with Digital Cameras. In order to see a real improvement, you need to increase by 4x the number of megapixels (i.e. to see a difference from a 2MP camera, you'd need to go to 8MP)

The megapixel myth was started by camera makers and swallowed hook, line and sinker by camera measurebators. Camera makers use the number of megapixels a camera has to hoodwink you into thinking it has something to do with camera quality. They use it because even a tiny linear resolution increase results in a huge total pixel increase, since the total pixel count varies as the total area of the image, which varies as the square of the linear resolution. In other words, an almost invisible 40% increase in the number of pixels in any one direction results in a doubling of the total number of pixels in the image. Therefore camera makers can always brag about how much better this week's camera is, with even negligible improvements.