On the off-chance that someone might find it useful, I've just uploaded my Rigorous Search extension to MW.org. This extension implements a full-page search facility, by the tedious method of individually searching the source of each page as stored in the "page" / "text" tables -- not the FULLTEXT index kept in the "searchindex" table for MySQL searches.
This is very slow, and almost totally useless -- except that it allows searching of the complete page source, not just the user-visible version of the text stored in "searchindex". So, for example, if you want to search for hyperlinks to a particular web site, this will work, whereas a MediaWiki search would not ("searchindex" includes link text, but not the link URL). You can also use it to search for particular markup tags.
A useful application is to search for novice users making "http://..." links into the wiki instead of using regular wikilinks, which causes pages to appear orphaned when they're not.
http://www.mediawiki.org/wiki/Extension:RigorousSearch
Ian