It can be found here :
Parallel Programming with Microsoft .NET
and read for free by clicking on the MSDN link!
A book that introduces .NET programmers to patterns for including parallelism in their applications. Examples of these patterns are parallel loops, parallel tasks and data aggregation with map-reduce. Each pattern has its own chapter. Each chapter includes a description of the problem, an example of where the pattern is applicable, and code that implements the solution. On this site you will find; a preliminary draft of the book, the accompanying code samples and answers to the end of chapter questions.
I received it in one of my emails from Microsoft, so enjoy!