I am currently developing an intranet site for my school using Moodle. I decided to create our internet with Moodle because I thought it would give my teachers good exposure to Moodle and the possibilities for their useage in a classroom environment. For compatability, I changed "Available Courses" to "Moodle Webs". So far, I have: enabled Active Directory authentication using multipe OU groups, applied a theme and made customization, changed authenticated login to automatically redirect to intranet.
I have lots more to do before I introduce my employees to this site, but I would definatley encourage anyone who is willing to do a little work to consider a "Moodle Intrantet."
You may view my site at: http://www.nbschools.net/moodle