And it's not for sales, but for something else entirely.
Dragon Quest IX has a "Chance Encounter" mode that allows players to share data with players they bump into in the real world via Nintendo WiFi. In dense Japanese cities, there's a good chance of bumping into another person with Dragon Quest IX in their DS with their game in "Chance Encounter" mode. How good of a chance?
Since being released in July 2009, the Dragon Quest IX "Chance Encounter" mode has been used 117,577,073 as of March 4, 2010. The game hasn't been released in North America or Europe, but will be out in those regions this July.