I haven't been at the zoo lately, but I have been learning about an elephant and a pig. Since I work so much with big-data apps that run on Hadoop and are written mostly in Pig, I have been playing around and reading up on both.
I built a three node Hadoop cluster at home using virtual machines: one node being the jobtracker+namenode and two nodes being tasktracker+datanodes.
So far, it's been a fun learning experience, but I still have much to learn -- and lots more that I want to learn like HBase, Hive, and Cassandra.