Note: this talk was back in November 2012. Since I'm rebooting the blog, and moving platforms, I'm just re-entering this item.
I gave an introduction to Cascalog talk at the Clojure Houston User Group a few months ago. Nothing earth shattering, but some of my meeting notes and other interesting links are available in Github.
An interesting item I ran across was a blog post comparing several languages you can use to write MapReduce jobs: Looking for a map reduce language.