A free (libre), open-source (GNU GPL), content management platform designed for group collaboration. Open Atrium is based on Drupal (running on Apache, with a MySQL database).
Web publishing software combining daily content management features with sophisticated site administration and development tools. With Saurus CMS you can easily set up any public website, extranet or intranet.
ycoon is a Python WSGI web development framework which allows XML processing pipelines to handle HTTP requests based on URI pattern matching. It is similar in intention to the Apache Cocoon framework. Pycoon uses sitemap file format compatible with Apache Cocoon Sitemap
ice is a track changes implementation, built in javascript, for anything that is contenteditable on the web. Conceived by the CMS Group at The New York Times, ice has been piloting successfully for articles written in the newsroom.