One thing I can't wait to see (maybe when the Go ecosystem is more mature) is Gojure, a Clojure that runs on top of the Go environment. That would be badass.

ETA: I realize that it just looks like I'm spouting opinions if I don't get into why it would be badass. Essentially, Go is a language designed for production systems in one of the most demanding large-scale software environments on earth. Compilation is rapid, and the language does a lot of things that force code quality. The problem is that it still feels a bit verbose. Putting a Lisp on top of that (and Clojure is my favorite Lisp) would be really interesting.