e.g. https://github.com/JetBrains/kotlin/blob/master/libraries/stdlib/test/CollectionTest.kt
You can also create a gist and say its Kotlin code and get syntax highlighting…
http://gist.github.com/2234425
Hopefully soon it’ll show up in the languages page
http://github.com/languages
If you see any gremlins in the syntax highligher, its all in pygmentize, so fork this repo
http://bitbucket.org/birkenfeld/pygments-main
and here’s the lexer to edit
http://bitbucket.org/birkenfeld/pygments-main/src/f8f6f70f3ded/pygments/lexers/jvm.py#cl-733
then submit a pull request