In my current project, a multiplayer game for mobile devices I only using Windows Azure Mobile Services as backend. The game will be available for multiple platforms and I will use Xamarin for iOS and android.
When using Xamarin I can reuse a lot of code if I using PCL (Portal Class Library) that i shipped with Visual Studio. When creating a new PCL-project you can choose which taget platforms the project will build for, in my case Windows Phone, Windows Store, Xamarin iOS and Xamarin Android.
In order to reuse so much code as possible I want to have the communication with my backend in PCL. When using Windows Azure Mobile Services I can have all communication there except for the code for authentication. But then I put an interface i PCL and each platform will have a specific implementation of the interface.
But where to find the Mobile Services assemblies for PCL? I installed Mobile Services via NUGET to my Windows Phone project (Windows Phone is my first platform). But Mobile Services was not just installed to my Windows Phone project, I also got the assemblies for PCL (and other platforms) i my packages folder. It enabled me to add the assemblies manually to the PCL-project.