Tech:OpenSearch Plugin for MediaWiki
You are running the OpenSearch extension (http://wikitravel.org/en/Special:OpenSearch).
The download link on the MediaWiki page that has this extension listed no longer works. (http://www.mediawiki.org/wiki/Extension:OpenSearch)
I have spoken with the developer (Gregory Szorc) and he no longer has a copy of the extension. He recommended asking someone who runs the extension on their wiki. Sorry to use a bug report to contact you, but I searched for about 30 minutes for a way to get in touch with you guys but couldn't find a single contact e-mail address. Please e-mail me the extension: email@example.com