At the moment, the FDA does bestow its approval on some apps, including a radiology tool called Mobiel MIM, but that approval at the moment is both pretty scarce and totally optional--it's a nice bonus if your app is FDA-approved, but the only organization an app developer really needs approval from is Apple. The FDA strikes a tone of total support for the surge in medical apps, but states concern that there is no real approval process that vets medical apps prior to release. If you've got a weird rash or a pain somewhere in your abdomen (could it be the spleen? What is a spleen, anyway?), or want to use your phone's sensors to monitor your organs (like a spleen, which I am 99% sure is in the abdomen), you might consult an app, and the FDA wants to make sure you're getting the right information.