From Raphael Haberer-Proust's website (http://diwww.epfl.ch/~haberer/syntax/scala_en.html):

Disclaimer

    * This is an absolutly basic version
    * Only keywords and simple constructs like comments are recognized
    * It is by far not finished
    * For comments and changes, please send me a mail to raphael.haberer-proust<at>epfl.ch
      (replace <at> with the apropriate symbol) 

Known bugs

    * automatic indentation does not work properly when using the syntaxic possibilities of scala (for example when omitting the ; after the return value) 

How to use it

In order to make vim find that file, add this line anywhere in your .vimrc configuration file:
let mysyntaxfile = "folder_path/scala.vim"

    * under Linux, Solaris, etc. usualy /home/username/.vimrc
    * under Mac OS X : /Users/username/.vimrc

If you want all the users of the system to access it by default, the best is to copy the file in vim's syntax folder 
(usualy /usr/share/vim/vim62/syntax/ or similar) and to add the line in the global configuration file (usualy /etc/vimrc)

If you do not have an own configuration file for vim, here[link removed] is mine, rename it to .vimrc and put it in your 
home folder 

Of course, syntaxic coloring must be switched on under vim. You can do this with
syntax on

    * For the users of the "operating system" from Redmond, as that system is said to be so easy to use, I'm sure they will get it by themselves ;-)