Conceptually, a Wikit is a searchable collection of inter-referential pages entered in a markup language and displayable/editable by several user interfaces.
Wikit functionality falls into four general and orthogonal categories:
1. Content and Title Keyword Search
As snitvfs points out, keyword and title keyword search functionality is directly supported by metakit views, using the mk::select facility -keyword. This could be provided by mkvfs.
2. Titles: Linkage between pages
Wikit provides the ability to reference pages in a [keyword] form within markup, where the keyword maps to a page title. This is implemented by a metakit view mapping referring->referenced pages, which is updated by inspection of pages upon creation and editing.
3. Markup Language with display conversions
4. User Interfaces - Tk GUI and HTTP/HTML
5. Revision History
This could be provided by a versioning virtual filesystem