In MediaWiki, Wikilinks point to articles from the default namespace (= "article"). This makes sense since MediaWiki doesn't have the capability to extend the amount and type of content types - there is a limited number of potential link targets, e.g. discussion pages, or user pages.

In the Drupal world it's pretty different. Imho we need significantly more flexibility how existing and/or nonexisting Wikilinks are handled.

a) Existing Wikilinks

Example use case: On one site I would need the capability to make Wikilinks not point to node titles, but to a user configurable CCK text field (e.g. node titles are a movie's title plus year and land of production; Wikilinks should point to just the title, which is stored in a multivalue CCK field).

Node title: Cinema Jenin (Israel/BRD 2012)
CCK field "Movie title": Cinema Jenin
Link to node by node title: [[Cinema Jenin (Israel/BRD 2012)|Cinema Jenin]]
Link to node by CCK field: [[Cinema Jenin]]

Other default Wikilink targets might be taxonomy term, or user/profile pages (note: some of this is already possible by setting up customized Interwiki links). Maybe we should think about pluggable handlers for existing links?

In MediaWiki, there is a mechanism to guarantee unique "node" titles; MediaWiki Filter currently can not mimic this; so the default behaviour is that Wikilinks might point to multiple Drupal nodes. To mimic MediaWiki's behaviour, we can use the 'Wikitools' module; however, this does not work when nodes are created programatically, and it does not fix duplicate node titles in exisitng websites. 'Wikitools' is a workaround; a better approach would be to handle duplicate node titles (or even better: ambiguous Wikilink targets), e.g. by a machine-generated page, similar to those created by Apache's 'Speling' feature.

b) Nonexisting Wikilinks

Currently, MediaWiki Filter can only handle "red links" for one fixed content type. That's a nasty limitation to create new content on a real Drupal site with multiple content types, and it usually requires a lot of refactoring and changing the (default) node type afterwards.

Ideally, MediaWiki Filter would allow to select the content type to be created, e.g. with an inline dropdown menu on the nonexisitng link. E.g.

Create new node of content type
------------------------------
article
blog
poll

Another frequently requested feature would be to (optionally) not create new content, but to perform a search (either on node titles, a CCK text field, taxonomy terms, or maybe even a combination of those).

Maybe we should think about pluggable handlers for nonexisting links as well? ;)

These ideas are just early thoughts, based on user feedback from several live installations. I'd like some feedback about this kind of extensions before starting to think about potential ramifications of an actual implementation.