The Java 8 Pocket Guide was just released last month: (http://shop.oreilly.com/product/0636920033318.do)

This pocket guide aims to quickly provide answers for those developing or debugging Java programs.  In this edition of the Java Pocket Guide, you will find basic coverage on the new Data and Time API and Lambda Expressions.

GoodReads is currently running a book promotion where you can win a free Java 8 Pocket guide.  This promotion runs until June 1st, 2014: https://www.goodreads.com/book/show/20976171-java-8-pocket-guide

Thanks,

Robert Liguori, Author