Deciding against creating separate Xamarin components at this time – NuGet packages are more re-usable and easier to manage.

You can add the NuGet Package Manager to Xamarin Studio to make it easier to install NuGet packages, see:
http://barambani.wordpress.com/2013/10/07/add-nuget-package-manager-and-servicestack-to-xamarin-studio-projects-2/

Whilst the PCL ServiceStack clients that support iOS and Android are being maintained on: https://github.com/ServiceStack/Hello