With Java taking a long overdue step toward functional language capabilities, the Java release scheduled for next year (2013) should provide the Java development community with a language feature that results in it providing a serious and compelling alternative to Scala as a JVM language with functional capabilities.
Evolution of Java, as a language, has stagnated somewhat during the last decade. Since the introduction of Generics nothing of major significance has been delivered. However, JDK8 is going to be a game changer, specifically by the introduction of lambda expressions.
Get ahead of the game by getting involved in debate and education around lambda expressions directly with a Java book author (Java Generics & Collections - Maurice Naftalin) and take the opportunity to learn, discuss and debate the new feature. You will notice that Maurice Naftalin has also strong associations with the Oracle Java Language & Tools team.
In order to join the discussion and debate go to Maurice Naftalin's Lambda FAQ