Automne is an open-source and intuitive CMS. It works on LAMP architecture.
Users can edit the websites in a WYSIWYG environment.
Developpers can quickly add modules via the integrated app generator without necessary knowing PHP, just XML.
Automne comes with a built-in validation workflow and can manage groups and users based on roles (necessary for extranet and intranet)
Automne can handle multiple websites on different domains and multiple languages.
Source code is hosted on Launchpad : https://launchpad.net/automne/