Last modified: 2013-03-26 11:25:20 UTC
It should be possible to search Wikipedia using Boolean operators, e.g. vanity AND NOT spam finds anything containing "vanity" but not "spam" (and definitely not the words "and" or "not"). This might need an "advanced search" form for a user-friendly implementation.
In current notation that would be: vanity -spam
Although it's somewhat buggy ATM
[Merging "MediaWiki extensions/Lucene Search" into "Wikimedia/lucene-search2", see bug 46542. You can filter bugmail for: search-component-merge-20130326 ]