Basho Riak: An Open Source Scalable Data Store
From the website:
Riak is a Dynamo-inspired key/value store that scales predictably and easily. Riak also simplifies development by giving developers the ability to quickly prototype, test, and deploy their applications
A truly fault-tolerant system, Riak has no single point of failure. No machines are special or central in Riak, so developers and operations professionals can decide exactly how fault-tolerant they want and need their applications to be.
The video from Ga Tech NoSQL conference in 2009 is worth watching.
Their implementation of MapReduce: is targeted (doesn’t have to be run against entire data set), can be setup as a stream (store and send through mapreduce), or used with the representation of relationships as links.