Akira Watanabe, manager of Olympus Imaging's SLR planning unit, told the press at the Photo Marketing Association convention (PMA09) that 12 megapixel is enough for covering most applications most customers need. ARS Technica agrees, and adds that even 12 megapixel is overkill for most users.
And for casual users, whose images largely end up on sharing sites like Flickr, Picasa, or PhotoBucket, even 12MP is overkill. With a decent lens, something in the 6-8MP range will more than suffice. Keep in mind that with the increase in megapixels comes a resulting increase in file size. So shooting hundreds or even thousands of 12MP images means larger memory cards, more space eaten up on hard drives, and more time sorting and editing—all for images that are likely to end up viewed at no larger than 800 x 600px... or about half a megapixel.