Standalone pedometer barely need any battery to run, could they have stuck the hardward inside the 3DS?

If so, it would actually allow you to turn your 3DS off while having the pedometer running, no?

It has to, it's Japanese! How will Japanese children defend themselves from Pedobear without it?!?!

I would say they are just using the gyros they are using for the tilt controls 

Most pedometer algorithms use accelerometers to detect movement from side to side.

Just go download any pedometer app on the iphone and shake your phone side to side and see what happens.

Sorry for double post.

But by the way, pedometer algorithms really don't require a high sample rate, so you can just live the accelerometer in some low power mode only sampling once or twice a second to make a pedometer.