It’s important to understand and take full potential of the MEF, so Windows Communication Foundation (WCF) is a bit outside the scope of the upcoming tutorials, but will be addressed in one tutorial sooner or later for folks wanting to use web services.
Never used SignalR, but I am bias when it comes to ASP.NET. That is, I avoid it. If it is easy to use and production ready and does everything you need then go for it.