The new mediawiki supports external editors, this is about the same as the hack I posted a few days ago. The nice thing about it is, is that you can edit about any file or page that's uploaded or written.
The page edit part of the program very much like the program I created. The only problem is that it uses regexe instead of a more stable solution like WWW::Mechanize. The support for editing files is really good.
A more elaborate system would let you edit spreadsheets on the wiki (with an external program like Gnumeric). The problem with this is that not everyone can edit all types of files.
The editing of pages with external editors is a nice addition to mediawiki.