All about Async/Await, System.Threading.Tasks, System.Collections.Concurrent, System.Linq, and more…
Despite the similarity in naming, the System.Threading.Tasks.Parallel class and the System.Activities.Statements.Parallel* activities in WF4 are largely orthogonal in the scenarios they address. However, WF4 activities and the new parallel programming types in .NET 4 can be used together to great advantage.
Ling Wo and Cristina Manu wrote a paper, Integrating Parallelism with Windows Workflow Foundation in the .NET Framework 4, that explores the similarities and differences between the two API sets, and demonstrates how to integrate the Task Parallel Library and WF4 to support the development of multi-threaded applications.
(This paper and many more are available through the Parallel Computing Developer Center on MSDN at http://msdn.microsoft.com/en-us/concurrency/ee851578.aspx.)