Want an open-source, free CMS? Low-end CMS's like WordPress are proliferating; high-end CMS's like Alfresco are also available. What about the middle?
Content Management Systems (CMS) aren't the most sexiest applications in the world. When you think CMS, you probably think Vignette, Interwoven or a similar enterprise-level product. Those systems are usually bulky and difficult to use. At the other end of the spectrum are blogging platforms, such as Movable Type or WordPress, which are renown for being fairly lightweight and easy to use - but often they lack the high-end functionality required in a CMS (content approval process, version control, reporting, etc).
In the middle of this spectrum (Enterprise CMS -- Blog Platform) lies SilverStripe, an open source CMS system developed by a small company out of Wellington, New Zealand. It has a simple web interface and was built using PHP5, an alternative developer framework to the more hyped web 2.0 framework Ruby on Rails. SilverStripe was recently named as one of 5 finalists in the Most Promising Open Source CMS Award, part of the 2007 Open Source CMS Awards held by Packt Publishing. Source