The Social Media Classroom is a new project started by Howard Rheingold which offers an open-source Drupal-based web service to teachers and students for the purpose of introducing social media into the classroom. The service includes tools like forums, blogs, wikis, chat, social bookmarking, RSS, microblogging, widgets, video conferencing, and more.
"I own the collection of comments on my blog, and you own the comments you've placed on my blog and all others. I should be able to back up a complete set of comments on my blog, and also back up a copy of all comments I've placed on all blogs."