Our Fine Arts College wants to deploy Moodle, and one thing they'd like is to continue the color-based theme of the differnet schools (Art, Visual Communication, Digital Arts, etc) from the Fine Arts homepage. Is there a way to set up a custom theme that would change the stylesheet based on the category of the course you're in, and if you're not in a course, use a default? It seems like this should be similar to the "different stylesheets for languages" post, but it may be more complex. I tried to figure out the breadcrumb system you were using to see if I could just backtrack through the database and find the course category, but I got all turned around, and decided to consult the source. :D
Currently the print_header() function in cvs:/moodle/lib/weblib.php that prints the header that loads the style sheet makes the $course object global. Thus within this function you can simply get at the category from $course->category. You can then use this information to decide which stylesheet to load.