My intention with the markItUp module was to ship it with the 'default' markItUp button set, probably the 'HTML' set (available separately, and not yet included), and to do a 'filtered html' set to match Drupal's input format of the same name.

Anything beyond that - people wanting to use the Markdown or Textile sets, for instance - could be accomplished by the user installing the necessary sets. (Info on how to do that is already in the README.txt.)

I'll be working on this soon. Wanted to post it first, though, so others could respond with their thoughts.