Here's a presentation on datacentres and MR my colleague and I gave to the local university this week, "My other computer is a datacentre". MapReduce was demoed on a different dataset from normal (scanned bluetooth devices from a static location) and implemented in Erlang, because the students are learning functional languages and it is easier to show the concepts when you really do have a stateless runtime underneath. The overall theme though, is how you run things like this in real datacentres, which is why I have photos of some of the Yahoo! Hadoop team and one of their datacentres.
http://www.slideshare.net/steve_l/my-other-computer-is-a-datacentre-presentation
