Please update documentation how to get started with realtime push using SignalR and Mobile Services:
http://azure.microsoft.com/de-de/documentation/articles/mobile-services-dotnet-backend-get-started-signalr/
The blog post here (http://blogs.msdn.com/b/azuremobile/archive/2014/05/30/realtime-with-signalr-and-azure-mobile-net-backend.aspx)
does not answer how to work with SignalR and Mobile Services in detail.
Especially connection and authorization details. Please provide information about Xamarin + SignalR + ServiceHub.
Also using the latest NuGet-Packages for the service Project will fail. Currently you'll have to use SignalR libraries 2.1.0. It was try and error to get through this :(
Hope you are able to update the doc soon.
Thanks in advanced!