This is just a study based on Damian Nenow workflow presented on Siggraph this year.
It's really rough, but it's possible to get incredible results like Damian did.
Take a look here, the whole presentation is awesome: vimeo.com/27716580
The way he did the clouds on "Paths of Hate" is a fantastic solution for rendering fast and realistic.
Thanks to Damian for being patient and answering some of my questions =D
Also, Eugene Mishibinijima, who did a great tutorial explaining all the process: vimeo.com/28004567
p.s.: Lucca is the name of my first son who will be born in february next year! =D