Semantic MediaWiki (SMW) is a free extension of MediaWiki – the wiki-system powering Wikipedia – that helps to search, organise, tag, browse, evaluate, and share the wiki's content. While traditional wikis contain only text which computers can neither understand nor evaluate, SMW adds semantic annotations that let you easily publish Semantic Web content, and allow the wiki to function as a collaborative database.
"Collaborative Knowledge Management, powered by the Semantic Web Wikis and social software have revolutionized the ways we create and distribute knowledge. The Semantic Web has already begun to transform the ways we maintain, discover and share knowledge across platforms. The KiWi - "Knowledge in a Wiki" - project proposes a new approach to knowledge management that combines the wiki philosophy with the intelligence and methods of the Semantic Web."