When I started ikiwiki in 2006, there were no other existing systems that filled quite the niche of generating a static html wiki out of markdown files stored in a VCS. My first blog about ikiwiki looked at some projects that were semi-close, and found them wanting.
Gitit is a wiki backed by a git (or darcs) filestore. No static rendering here; pages are generated on the fly. It's written in Haskell and uses the amazing PanDoc to generate html from markdown or many other formats.
Markdoc statically builds a wiki from markdown source (which can be in a VCS, if you check it in). It includes a built-in webserver to ease serving the generated static html.