According to the Daily Record, Liverpool John Moores University found that Wii players who play 12 hours a week or so burn 1830 calories, or the equivalent of around 27 pounds a year. 12 hours a week of Wii is more than you think, but certainly 30-60 minutes a day is pretty conceivable. That's roughly equivalent to a 20 minute aerobic exercise, according to the article.

Over on Kotaku, Flynn De Marco suggests that Nintendo should just go ahead and start making a Wii Fitness series. Based on the work I've done on exergames (there's a chapter in my forthcoming book), I'm not so sure that straight simulations of fitness are as effective as non-fitness-themed games that adopt some of the same motivational strategies of the personal trainer. DDR and Donkey Konga are like this: they provide small, continuous incentives for physical movement. Of course, the commercial rhetoric of Wii Aerobics or Wii Pilates would certainly enjoy strong response.