Watched a set of 3 lectures run at Google, by Aaron Kimball, on MapReduce was inspiring to me. I feel like I have a much more solid grasp on MapReduce after watching these. I really liked how it started out with some basic functional programming and socket theory, then moved into how MapReduce builds on the basic principle of Map and Fold. Well worth the 3 hours!
http://www.youtube.com/watch?v=yjPBkvYh-ss
Thank you Google and Aaron Kimball!