Apple is expected to announce a health app initiative at WWDC 2014 on Monday, as part of iOS 8. The center of this initiative is expected to be an app called Healthbook. It addition I think there will be an API and perhaps a health focused app ecosystem as well.
The rumors about Healthbook have been circulating for months. And just yesterday MacRumors discovered that trademarks for Healthbook, HealthKit, and iResearch had been filed months ago, likely by or on the behalf of Apple.
I think this will be huge. Competitors are already begin to ship simple products and announce plans for bigger things.