Just finished reading ch23 in the excellent 'Beautiful Code' http://oreilly.com/catalog/9780596510046
on Distributed Programming with MapReduce. I understand that MapReduce is a programming system designed for large-scale data processing problems, but I have a hard time getting my head around the basic examples given and how I might apply them in real world situations.
Can someone give a simple example of MapReduce implemented using either java, javascript or actionscript?