They clearly mention this goal in their blog post:
http://blog.wikimedia.org/2013/08/01/future-https-wikimedia-...
http://blog.wikimedia.org/2013/08/01/future-https-wikimedia-...
Enabling perfect forward secrecy is only useful if we also
eliminate the threat of traffic analysis of HTTPS, which
can be used to detect a user’s browsing activity, even
when using HTTPS.