In layman’s terms, you can now use the ultra-powerful divide-and-conquer strategy of MapReduce to solve problems involving large datasets on a pay-only-for-what-you-use basis. The complex framework of a MapReduce system (break a job into many pieces, farm it out, collect the results) is provided for you, and you’ll pay Amazon just pennies an hour for computing resources.
For most of you, the appropriate response is “So What?” But for those who need this capability, the response is indeed, “Holy Crap!” MapReduce, which does much of the magic at Google, is now available to everyone with a problem to solve and a credit card.
See my print article, 2009: Cloudy, with a Chance of Windows, for a concrete example of MapReduce in action. It’s powerful, and now it’s also cheap and easy.