I'm quite satisfied with the current crop of functional languages, what I'm waiting for is widespread adoption so I can stop working with Java to pay the rent. What do I like about it? The expressiveness of FP and immutability-by-default (makes concurrent programming much less headache inducing), are two major benefits, I suppose.

Well, you're probably right... but I think that says more about your average programmer than about the utility of lambda expressions. The biggest complaint I hear about Scala (or any other FP language) is that it's too hard to learn. I've even had a coworker tell me that since Java does "everything", there is no need to learn any other language (I didn't know how to respond to that).

I'm still waiting for that FP renaissance....

Programmers that really cared about things like lambda expressions have already moved on to Scala and/or Clojure (and of course, it's not as if lambda expression support is the only thing those languages have going for them over Java). I work on a mixed Java/Scala codebase, and we just finished upgrading from JDK6 to 7. I don't see us tackling an upgrade to JDK8 anytime soon (probably won't be until JDK7 stops getting security patches).