Just out today, West Virginia Public Employees Insurance Agency is sponsoring a study on the affects of playing Dance Dance Revolution on "boosting activity" in overweight kids. From the CNN article:

It's nice to see sponsored research on this topic, but... couldn't we write the results right now without doing the study? Presumably the very act of participating in the study would "boost activity" in the test subjects. I think I'll hold out for a longitudinal study, or one comparing the relative impact of DDR on certain kinds of weight loss or exercise.