Club Skill has an article on Nintendo's controller and it having ANOTHER button, not shown ever before:
This is a scan from the upcoming August issue of Nintendo Power magazine. You can see a woman holding a black Wiimote, but then you see a purple colored button on the underside of the controller.
This button on the controller has not been in any photo, at all. It wasn't even shown at E3. No mention of it has been made.