A link to this project was posted on the Semantic MediaWiki developers mailing list.
In the project's own words: "The dbpedia.org project approaches both problems by extracting structured information from Wikipedia and by making this information available on the Semantic Web. dbpedia.org allows you to ask sophisticated queries against Wikipedia and to link other datasets on the Web to dbpedia data. "
The website has a demonstration of the kind of semantic information that can be extracted from the main infobox on English Wikipedia's Innsbruck article.
"The dbpedia dataset currently consists of around 25 million RDF triples, which have been extracted from the English, German, French, Spanish, Italian, Portuguese, Polish, Swedish, Dutch and Japanese version of Wikipedia."
An example of reuse of Wikipedia data in a very useful way.