Websites using ISO 8601

Consistent

http://www.postgresql.org/ (50% ISO, rest other)
https://www.python.org/ - on that page consistent, but if clicking to Upcoming events or Latest news other formats are shown
https://www.mediawiki.org/wiki/MediaWiki - on this page almost consistent, but the interface message on the bottom says "19 July 2013, at 17:24.". Page history page uses "12:25, 9 June 2013‎ ‎".
- https://www.mediawiki.org/wiki/Talk:MediaWiki on top "Archives: 1 (by 2005-08-19)", right-hand "15:02, 28 May 2014"
- https://bugzilla.wikimedia.org/buglist.cgi?bug_status=PATCH_TO_REVIEW&order=bug_severity%2Cchangeddate&query_format=advanced on top "Thu Jun 5 2014 11:09:16 UTC", right hand "2014-05-15"
- https://git.wikimedia.org/commit/mediawiki%2Fextensions.git/443c6ed0064fa991f91167285bdce2685fb7edde "Wednesday, May 28, 2014 08:59 +0000"
php.net site uses at least 9(!) date formats : https://bugs.php.net/bug.php?id=66157
https://launchpad.net/ubuntu/precise/+source/kolab-cyrus-imapd/2.2.13p1-0.3build1
- "Published on 2011-11-16"
- "Wed, 16 Nov 2011 09:37:29 +0000"