Elgg, started in 2004, is an open source social platform which powers all kinds of social environments - from education to business and sports such as rugby. If you are looking to create your own social application or want to build and run a site for your organisation, Elgg is a great choice as it provides the building blocks you will need.
Join the world's first and largest social networking site dedicated to education and educational technology. Launched in 2004 and with over 19,000 members there is something in here for everyone interested in education
I have only briefly trialled it but user interface is very bog standard education document look and feel. I reckon it's for administrators not students? Maybe try Buddypress or Elgg?