http://stackoverflow.com/questions/40075/generic-list-extensions-in-c-sharp
According to this link Functional Programming in C# 3.0: How Map/Reduce/Filter can Rock your World the following are the equivalent in C# under the System.Linq namespace:
map –> Enumerable.Select
reduce –> Enumerable.Aggregate
filter –> Enumerable.Where

http://en.wikipedia.org/wiki/MapReduce
The frozen part of the MapReduce framework is a large distributed sort. The hot spots, which the application defines, are:
an input reader
a Map function
a partition function
a compare function
a Reduce function
an output writer

Google: Cluster Computing and MapReduce
http://code.google.com/edu/submissions/mapreduce-minilecture/listing.html

Parallel LINQ Running Queries On Multi-Core Processors
http://msdn.microsoft.com/en-us/magazine/cc163329.aspx

Introduction to MapReduce for .NET Developers
http://www.developerzen.com/2009/05/06/introduction-to-mapreduce-for-net-developers/

open-source software for reliable, scalable, distributed computing
http://hadoop.apache.org/
http://www.infoq.com/cn/articles/hadoop-intro