Here are some nice YouTube videos on MapReduce
http://www.youtube.com/watch?v=yjPBkvYh-ss
http://www.youtube.com/watch?v=-vD6PUdf3Js
http://www.youtube.com/watch?v=5Eib_H_zCEY
http://www.youtube.com/watch?v=1ZDybXl212Q
http://www.youtube.com/watch?v=BT-piFBP4fE
Also, here are nice tutorials on how to setup Hadoop on Ubuntu
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-single-node-cluster/
http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-multi-node-cluster/