There continue to be announcements about Apple's medical research software platform, an interview with Steve Friend gives some insights into how ResearchKit and HealthKit were born.

More recently

IBM (NYSE: IBM) today announced its Health Cloud and Watson cognitive computing capabilities will support health data entered by customers in iOS apps using Apple's ResearchKit and HealthKit frameworks. The move, which complements IBM's new Watson Health business unit, will arm medical researchers with a secure, open data storage solution, as well as access to IBM's most sophisticated data analytics capabilities.

ResearchKit is an Open Source framework developed by Apple intended to be used for building apps for medical research.

There is more information here

and the GitHub repository is here

To get the latest stable release

git clone -b stable https://github.com/ResearchKit/ResearchKit.git

Ars Technica will be reviewing in detail over the next few days.

I've added ResearchKit to the MobileScience site.