I work at MITRE where our team makes extensive use of Semantic Mediawiki. We've written a Mediawiki extension which we plan to open source soon that produces a network graph of wiki links. It is not only useful as a graphical navigator within a wiki but also helps us "see" the greater network of SMW wikis in our farm (50+).
In addition, we've leveraged SMW and it's results formats in hopefully novel ways. We hope to present at this years SMWCon (we've been wanted to for a while).