Google launched Google Health back in February 2008. Today, Google is integrating Google Health content into the search results via the classic OneBox section of the page. You should be able to see the Google Health OneBox for medical related searches, such as for [asthma] or [diabetes].
Here is a screen capture of the OneBox result for Asthma:
As you can see, Google provides a quick definition of the condition and then gives you a link to either Google Health, Mayo Clinic, Medline Plus or WebMD. Note, not all of these links will be available for all health-related queries.
I asked Roni Zeiger, the product manager for Google Health, about monetization of Google Health. He told me it is about getting the answer as quickly as possible to the searcher. They have no current plans or even future plans to add ads to the Google Health property.