The site has posted complete recreations of leaked screenshots from the Healthbook which can also be seen below. You'll notice that the new app looks a lot like the Passbook app.
Healthbook has cards for Bloodwork, Heart Rate, Hydration, Blood Pressure, Activity, Nutrition, Blood Sugar, Sleep, Respiratory Rate, Oxygen Saturation, and Weight. Tapping one of these cards opens it to reveal detailed information. For example, the Activity card shows steps taken, calories burned, and miles walked. Healthbook also has an Emergency Card that will would store the user's name, weight, eye color, birthdate, blood type, medical information, contact information, and organ donor status. It's possible that the Emergency Card could be accessible from the lock screen.
At this point its unclear where Healthbook is getting its data from. It could come from the M7 coprocessor, other apps, third party devices, or perhaps the rumored iWatch.
If the Healthbook app is dependent on the iWatch we may not see it revealed alongside the beta of iOS 8; rather, it could launch alongside the iWatch whenever it arrives.
More details in full report linked below...