We use SCSS where I work. If you're thinking about starting with it, I'd advise against that because the sass binary causes me a lot of problems. I like the language and the concept is good, but the implementation is a constant thorn in my side. All this expressive power rules, until you're driven to frustration just getting the damn thing to spit out a stylesheet.
I don't know this field very well, but perhaps a more mature CSS preprocessor would be better, or just hold off until this one isn't such a nightmare (no idea when that will be). Just my two cents.