Start to learn Hadoop

Background on Hadoop:
http://www.youtube.com/playlist?list=PLF82F6499E89E1BAE

Cloudera  Distributions. (KVM, VMware or VirtualBox):
https://ccp.cloudera.com/display/SUPPORT/Cloudera's+Hadoop+Demo+VM+for+CDH4
https://ccp.cloudera.com/display/DOC/Hadoop+Tutorial#HadoopTutorial-Purpose

Courses:
http://bigdatauniversity.com
http://www.ibm.com/developerworks/data/library/techarticle/dm-1209hadoopbigdata/
http://university.cloudera.com/courses.html
http://university.cloudera.com/onlineresources.html
http://university.cloudera.com/training/apache_hive_and_pig/hive_and_pig.html
http://hortonworks.com/hadoop-tutorial/hello-world-an-introduction-to-hadoop-hcatalog-hive-and-pig/
http://www.lynda.com/Hadoop-tutorials/Hadoop-Fundamentals/

Books:
"Hadoop: The Definitive Guide" by Tom White
"Hadoop in Practice" by Alex Holmes, Manning Pub.

Posts:
http://hadoopecosystem.whatazoo.com/
http://hadoopecosystem.whatazoo.com/home/training