How many megapixels are enough in a digital camera?

Well, an executive with Olympus, one of the leading high-end camera producers, says that 12 megapixels is enough.  Many experts agree, check out the article at Ars Technica.  You can produce great 8x10 pictures with a 7-8 megapixel cameras.  Consumers use megapixel size as the benchmark for how good a camera is.  The truth is that most of us cannot tell the difference in picture quality beyond 8 megapixels.  Can you tell?