I created a way to do lambda's in java 1.6 without changing: the JDK, the compiler, the ByteCode or the Syntax.
I vBlogged my thoughts here:
It's only a jar file, no special requirements or changes.
You can down load it here at www.approvaltests.com
You might also be interested in my similar addition of extension method in java
Here's the diagram of the syntax :
I also made a small tutorial here : http://blog.approvaltests.com/2010/10/java-lambdas.html