Dan, thanks, I'll look at semantic mediawiki.
SMW has means of using Dublin Core and any other vocabulary, but it does not embedd the annotations into the XHTML-header (as I know some webpages do with DC).
Markus, that would be a problem for me. Part of the reason I need DC on my site is to interact with applications such as Zotero [1], allowing researchers to grab bibliography/citation information from the page.