PLinq a.k.a Parallel Linq
Plinq which is an internal Microsoft project to make Language Integrated Queries LINQ, run in parallel without making the developer going into ugly details of concurrent constructs, and get the real benefits of writing declarative code that the compiler and / or system can make smart decisions to run the code better and faster.
However, PLinq is not applicable for all kinds of programs.
for more information read the full interview with Andres Hejlsberg.