Yay for Sass! 

Returns after commas, and added spaces after each selector. (it's Sass, let them breath since they're going to get compiled anyway)
Well, I use compass framework, you can take it [from there](https://github.com/Compass/compass/blob/stable/frameworks/compass/stylesheets/compass/css3/_text-shadow.scss "Compass Text Shadow ") and [there](https://github.com/Compass/compass/blob/stable/frameworks/compass/stylesheets/compass/css3/_box-shadow.scss "Compass Box Shadow "). They are quite complicated due to the fact that the number of variables can be varied. But for simple shadows I recommend using [these mixins](https://gist.github.com/garyharan/957284 "Useful scss mixins (rounded corners, gradients, text-field, button) ").