It's yet unknown whether the Wii's new Legend of Zelda game is planned for a 2010 release in Japan alone or worldwide--though the last Wii Zelda title Twilight Princess received a simultaneous worldwide release and the most recent DS entry Spirit Tracks was actually released in North America first. The game was given a very low-key announcement during E3 2009 by series creator Shigeru Miyamoto, who commented that he hoped to show the game at E3 2010. Miyamoto has hoped that Wii MotionPlus will be widespread enough for the game to be able to require it, as he's a big fan of archery and swordplay in Zelda.
On a successor to the DS line, Iwata said "[It will have] highly detailed graphics, and it will be necessary to have a sensor with the ability to read the movements of people playing."
The DSi is already able to achieve limited Natal-ish motion control through its built-in cameras, as seen in the DSiWare game WarioWare: Snapped! External accelerometers have been also used by games as far back as the GBA's Kirby Tilt 'n' Tumble in 2000.
Kotaku further relays that Nintendo will hold a press conference for the mysterious Wii Vitality Sensor in July "with the intention of putting it on sale as soon as possible."