Plexus is a Content Management System with the goal to provide a simple but extensionable system with in-page-editing functions. You can edit pages as you see them and add small components called widgets to your site, which make it very easy and flexible to customize your contents. Look at the screenshots or try out the demo version to leran more about Plexus.
Plexus uses rewritten (speaking) URLs, ships with a standard search function, dynamic generated sitemap.xml and atom feed, and uses an easy, PHP based, template system.
The project was started on October 1, 2009 and is released under MIT license - You wanna join?