Actually there IS some merit in going for more megapixels. It can actually increase the quality of your low res images as the colour filter array interpolation will have less error. So, even if your optics can't resolve more than 3mpix, the 3mpix image of your 5mpix camera (if CCD data postprocessing is done right) will be better than a 3mpix camera's. Of course, the best is if you have adequate optics, but with mobile phone-class camera a lot of corners have to be cut...