I still am going through Programming Concurrency on the JVM by Venkat Subramaniam.
I have hit a bit of a snag. I am on the chapter covering Actors. He uses the Akka library, but he uses an old version of it. A lot of the packages have changed, and I could not find some of the classes in the documentation. I would like to say that it is nice that they now have javadoc in addition to scaladoc. Frankly, I am not too thrilled with Scala. The Java code that calls Clojure STM classes still works.
Also: Venkat S was here a couple of days ago to speak at the Austin JUG. He gave the same concurrency talk I saw a couple of years ago at No Fluff Just Stuff. I took some notes, and I will post them in a few days. Some of the Java 8 stuff looks interesting.