The previous years conferences have been great! Wide range of technologies covered. Last year Guy Steele, and Doug Crockford gave a keynotes. Among my favorite talks last year were Nathan Marz on Cascalog, a data processing library written in Clojure, and Ryan Dahl on NodeJS.

Just noticed that Rich Hickey is giving a keynote this year. Really excited about this. I've watched some videos of his previous talks. He is one intelligent guy.