Here's what you can do in Google Health:
* create a health profile with information about your health conditions, medications, allergies
* import medical records from US hospitals that use Google's APIs to make the conversion possible. Unfortunately, the list of partners is almost empty.
* read medical resources, information about diseases
* find a doctor using Google Local Search
* use other health services that integrate with Google Health and can can import your data securely and use it for different purposes: calculate the heart attack risk, print your health history or share it with doctors. According to the FAQ, "Google Health is a PHR (Personal Health Record), but it is also a bit of a different model. We believe it's not enough to offer a place where you can store, manage, and share your health information. You need to act on your health information to better manage your health needs on a daily basis. This is why we provide a directory of online health services to you. You must elect to sign up with a service and decide what level of personal data you want to share in exchange for the customized services those companies offer."
Google Health wants to become the central place where you organize your health information and share it with people or services you trust. Since this information is very sensitive, Google takes a lot of precautions by using SSL connections and a separate privacy policy that clearly states: "You control who can access your personal health information. By default, you are the only user who can view and edit your information. If you choose to, you can share your information with others."
This is a big test of trust for Google and probably the most personal service ever offered by the company. While you can also enter your credit card information in Google Checkout, your location in iGoogle or Google Maps, personal information in orkut, Blogger and YouTube, Google Health is about your existence.
"Health information is very fragmented today, and we think we can help. Google believes the Internet can help users get access to their health information and help people make more empowered and informed health decisions. People already come to Google to search for health information, so we are a natural starting point," says Google. But there's a big difference between offering general health information and storing health records, so it will be interesting to see if Google manages to convince users that this shift is beneficial to them. Google could integrate more health information in the search results, the same way Microsoft shows information from HealthVault in Live Search and lets you collect it in your account. TechCrunch says that "Google promises never to advertise on Google Health".
(Small tidbits: Google Health is one of the very few Google applications created using Google Web Toolkit and its codename seems to be Weaver.)