A couple of days ago a patent for a Nintendo pedometer was revealed. Yesterday at the Nintendo press conference it was revealed this Pedometer is real and that it will be bundled with a DS game titled 'Your Life Rhythm'. Similar to Wii Fit/Brain Training the game basically has you connect the pedometer to the Nintendo DS/i and carrying the DS you walk. Other than that no other game details released.
Join MyDS to vote for your favourite story!
http://kotaku.com/5058461/nintendo-pedometer-is-for-ds-walking-game