Examples of C# 5.0 async/await vs. Akka actors vs. basic fork/join?

Both C# and Scala have adopted frameworks for simplifying doing asynchronous/parallel computation, but in different ways. The latest C# (5.0, still in beta) has decided on an async/await framework (using continuation-passing under the hood, but in an easier-to-use way), while Scala instead uses the concept of "actors", and has recently taken the actors implementation in Akka and incorporated it in