Semantic MediaWiki (SMW) is an extension of MediaWiki – the wiki-system powering Wikipedia – with semantic technology, thus turning it into a semantic wiki. While articles in MediaWiki are just plain texts, SMW allows users to add structured data, comparable to the data one would usually store in a database. SMW uses the fact that such data is already contained in many articles: users just need to "mark" the according places so that the system can extract the relevant data without "understanding" the rest of the text. With this information, SMW can help to search, organise, browse, evaluate, and share the wiki's content.
http://ontoworld.org/wiki/Semantic_MediaWiki
