Take a look to the 6mpixel.org site.

A more correct statement of this post title would be: having more MP doesn't give you better shots if the sensor size remains the same!

To have a more precise digitalization of a scene, having more pixels isn't sufficient; you have to have a corresponding increase of the sensor size or a better quality of the sensor sensibility; without those conditions, you will only capture more thermal noise: this is what I can understand from their site and what I can subscribe.