Haskell, for starters. But more seriously, the motivation is to have a wiki with the capabilities of Pandoc: a bunch of formats -> a bunch of other formats. One comment already pointed out literate Haskell, which is nice.

Pandoc is excellent. But it's also available for ikiwiki, since I did a quick port a year ago: <https://github.com/dubiousjim/pandoc-iki>. I don't claim it's (yet) as well-integrated as it is with gitit.