I see a number of apps besides Find Friends now only allow location services 'while using' . This is, I believe ,a new category and I am baffled as to the reason for it. It certainly reduces the usefulness of Find Friends.
It's not new, in the sense that it's new behavior. It's only new in that Apple is now being clearer on whether apps use location services only when the app is open, or whether they might be using location services even when they are in the background.
Apps already did one or both of these before, but you only had an ON/OFF choice for control. If it was not spelled out in the app's description or obvious from it's features, you did not know.
By default, apps that have not been updated for the new location permissions only give you the Off or Always on choices, and you still don't know if/when they are using location service. Going forward apps should start giving you choices appropriate for that app.
Most will start using the While Using App. This is how the majority of apps have always worked. Very few apps need to access your location until you open. Most photo apps, for instance, only need to know where you are when you are taking the picture. (if you want them to include that information in the photo)
Some will continue asking for the Always option. One example would be apps that offer notifications based on your location. They will need to occasionally check your location to see where you are, even if they are not open. Some of the activity tracking apps might do this as well.
And a few apps will give you all three choices. Off / While Using App / Always. Those apps will probably have more limited features, depending on how much you restrict their access to location services. FaceBook is one of these.
The key here is that Apple has not stopped apps from using Location Services in the background. What they have done is make sure that you know when your apps can access your location, and given you more control over restricting that access.