The new Parallel Programming features in .NET 4. Formally known as the Parallel Extensions Library for .NET, these new features have graduate from DevLabs and are available out of the box in Visual Studio 2010. These exciting new features in .NET help developers take full advantage of all those cores now shipping in modern computers. It’s massive threading made easy.
Task
—Represents an asynchronous operation.
Parallel programming is introduced in C# 4.0 using the Task libraries. There are many aspects of Parallel programming and how to use the Task libraries. Task can be used as Threads in multi-threading programming. The Task class is a great representation for any asynchronous operation, even those implemented purely as asynchronous I/O.
We can use the Task for defining asynchronous methods and the main feature of task is the co-operative cancellation. This is against the Thread manipulation, where we can forcibly cancel a thread. Also a task can use the same synchronization context from UI thread using the TaskScheduler.
For more details
http://blogs.msdn.com/b/pfxteam/
http://msdn.microsoft.com/en-us/concurrency/default.aspx
