This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
The concurrency update for 5.0 is relatively huge. This was one of the reasons why our book was practically a total rewrite. Some stuff, like the atomic libraries, required new techniques -- in this case, understanding optimistic locking.