"Revolutions just spread blood. Evolution - this is something that changes in the long term." (Marjane Satrapi)
Java SE 8 is scheduled for release next month, i.e. March 2014. From a Java EE point of view, the Java EE 7 specification requires at least Java SE 7. So clearly, nothing prevents you from using Java SE 8 with Java EE 7.
A lot of us are in fact using early builds of Java SE 8 with GlassFish on a daily basis without any problem!
The introduction of Lambdas Expressions is another key feature of Java 8. Lambdas basically add Closures support to the Java language, they allows to pass functionality as an argument to another method. Lambdas are seen as one of the most fundamental evolution in the Java platform since Generics (if not more important than Generics!). Lambdas leads to a different way of thinking, a different (and cleaner) way of writing code.
Java EE developers shouldn't wait and need to learn how to use Lambdas Expressions today as they are not incompatible with Java EE 7. Here is, for example, a post from Gerard Davison of the JDeveloper Team that shows Lambdas used with the WebSocket API.
If you are using Lambdas or any other Java SE 8 feature(s) today in Java EE, please let us know!