few years ago i read something that said that most megapixel ratings are essentially lies just like the sizes of the old CRT monitors or hard drive sizes today. i forgot the tricks the camera companies used to avoid getting sued, but the article mentioned that if you find a good camera with a good lens you'll do better than buying a camera with a high MP but crappy lens.
I'm not complaining that the iPhone 3GS has only got a 3 megapixel camera, just correcting the error of the previous poster who said it had a 5 megapixel camera.