This is a good starting step in a great direction.
Nintendo is reaching a consumer with leisure money to spend, in a place where they don't have deadlines, kids to pick up from school, or a half hour lunch break. I wonder how many people the entirety of six flags across North America takes in. I also wonder if people will have to wait very long to play a Wii. Anyways, this way the Wii and possibly the DS will reach perhaps thousands of people a day, without much cost from Nintendo. This is a great target audience for Nintendo, too. It is the people who can afford and are interested in exciting forms of fun. They need to be careful, though, as you'd probably want to avoid a game like Brain Age here. Nintendo should put arcade-ish games in these stations, like Wii sports or perhaps even Elebits if they can. And maybe showcase the VC, too, since everyone knows Sonic and Mario. This probably isn't the place for Red Steel or Zelda. Other games that would work well are Excite Truck, possibly Trauma Center (Though that depends on the area set-up), and even Rayman, in the plunger gun modes, especially.
This could give Nintendo a considerable boost if they play it right, and no market analyst would even understand where it would have come from.
Now, if Nintendo wants Brain Age to appeal to an audience, they'll have to try this somewhere else, where the target people also have leisure time, but aren't looking for the same type of excitement as an amusement park gives. I really thik they need to consider placing them in the waiting room of doctor's offices or at pharmacies personally. That's just me, though.