I'm a pediatrician who is interested in obesity, so I do follow this. There is a literature on this that the kinds of video games that children choose, or are encouraged to choose, do have an impact on energy expenditure. So it turns out that some of these interactive games really do have a big impact—and, again, it's not one-size-fits-all.
The interesting thing about the Wii exercise is that visible minority teenage girls take to that very positively, whereas boys might go for competitive sports or go to a community centre. So it is a real opportunity to intervene to prevent and treat adolescent obesity, anyway.
There are researchers around the world, including in Canada, looking at the potential of using what kids are playing with, but to reduce and prevent obesity.