The language used on this wiki depends on the language preferences of your browser, and these usually depend on the setup of your operating system.
Further, the title of the table of contents, the output of the Oddmuse:UseDiff and Oddmuse:Rollback Extension appear in the language of the last person who edited the page, not the language specified by your browser. This is because OddMuse? uses the same language variable in the environment for producing these localized texts.
Note that all the various languages are in a single wiki. There are not enough non-English pages to warrant a separate wiki.
If you follow the English link on the SiteMap, you should end up on the English script.
You can also use the English prefix (eg. English:DrewAdams) to specifically link to a page using the English interface.
If you want readers following a link to the wiki to use a particular interface, use the ISO language code in the URL: http://www.emacswiki.org/cgi-bin/emacs-en will use the English interface.