I work at a small college that wants to make "sites" for all of the academic departments (~30). I managed to talk them out of their original idea: 30 individual Wordpress installations. What a maintenance nightmare!

What I'm looking for is a CMS (preferably Python or PHP, as those are my areas of expertise) that can automagically create a subsection (or subsite, whatever the appropriate vernacular) complete with user and a couple of headings based on a template. So, I could just click a button and have a new subsection for a new department complete with its own authorized user, and default subsection headings/menu/pages.

Is this just wishful thinking? I don't mind getting my hands dirty (this would be the whole of my job duties), so what platform would be a good starting point for something like this? Open source is a must for me as I have literally no budget, and I'm probably going to have to dig pretty deep into the application.