Lambdas are now available within Java 8 in the form of JSR-335 - Lambda Expressions for the JavaTM Programming Language

UPDATE: JDK8 has now been released which contains project lambda. It's worth grabbing a copy of Java 8 in Action currently still MEAP.

Have a read of Brian Goetz articles relating to lambdas for a decent understanding of how lambdas are implemented within JDK8 while also gaining an understanding of streams, internal iteration, short-circuiting and constructor references.. Also check out the JSR's above to get further examples.

I've written a blog on some of the advantages of using lambdas in JDK8 called The Power of the Arrow, also NetBeans 8 has great support for converting constructs to JDK8 which I've also blogged about Migrating to JDK 8 with NetBeans.