Where I work, the design and development departments are totally separated, however we (the design department) are responsible for managing the CSS for our sites. Typically, new CSS needs to be released to the production server far more often than new website code. Because of this, we are deploying the CSS separately, and it lives outside source control.
However, lately, we've run into a few problems with new CSS not being synched for up site releases, and in general the process is a huge headache. I've been pushing to get the CSS under some kind of source control, but having trouble finding a good deployment method that makes everyone happy. Our biggest problem is managing changes that affect current portions of the site, where the CSS changes need to go live before the site changes, but not break anything on the exisiting site.
I won't go into the finer details of the weird culture between designers and devs here, but I was wondering what experience others have had in managing large amounts of CSS (50+ files, thousands and thousands of lines) that needs to be constantly updated and released independent of site releases.