I have created a special page extension that implements OpenSearch 1.1 (
http://opensearch.a9.com) for MediaWiki 1.5 and greater. More details can
be found at
http://opensource.case.edu/projects/MediaWikiHacks/wiki/OpenSearch and
http://meta.wikimedia.org/wiki/OpenSearch
Gregory Szorc
gregory.szorc(a)gmail.com