What makes a CMS a CMS? What features should a content management system have? Is a CMS a subset of other common knowledge management systems -- or does the CMS contains theses sub systems?
Core considerations for a CMS:
Content Management - Document management and related workflow
Content Creation (authoring) - Web based forms for content entry. Easy-to-use UI for editing (WYSIWYG editor)
Content Delivery - Separation of content from presentation. Publishing.