Restrict User edits

Hi,

I have set up a blog within a website and that has a main feed of posts coming from the admin.

I was hoping that if I added a user and give it Author (or whatever) rights, but not admin, that I can restrict this persons access to only posting on their blog roll. So say different apartments can post to their category, but not to others.

Is this possible?
This way I don’t need to set up a separate WP install for every single person who wants to add a blog within the company.

Cheers for the feedback.
Jeff