Currently xml:lang is set by $wgContentLang only. It's not good to search
engines to determine the real content language of a specific page. The worse
thing is, Wikimania 2007 site set xml:lang incorrectly to "wikimania2007".


By helps from Ping Yeh <ping.nsr.yeh@gmail.com>, the patch checks available
language codes of Template:Languages to set xml:lang dynamically. It's
particularly important to 
http://wikimania2007.wikimedia.org or other sites
used Template:Language to retain the impact of search engine optimizations.

Please refer to 
http://bugzilla.wikimedia.org/show_bug.cgi?id=10736 for the
patch. Thank you!

    Cheers,
/Mike Tian-Jian "b6s" Jiang/