The Wii Vitality Sensor debuted at the 2009 E3 gaming expo. Then it was too mellow for last year's and this year's E3. Why?
When asked this question earlier in April, Nintendo replied that it was still in development, but wasn't yet working on 99 percent of Wii players. Thus, it doesn't yet have a release date.
At today's Nintendo Q&A, Nintendo's Shigeru Miyamoto said that Wii Vitality Sensor development continues, but the device isn't as consistant as Nintendo wants it to be.
Nintendo is continuing development on it and other sensors to bring out the experience.