The official Facebook Developers group is still directing users to facebook.stackoverflow.com for technical issues.
Quoting from the groups "about" section:
This is not a forum for asking detailed technical questions, use http://facebook.stackoverflow.com/ for that.
That mini-site/tag-filtered-site no longer exists and simply redirects to a wildcard tag search - should this link still be distributed by Facebook? I think not.
Perhaps the SE team could request a change so that the section reads something on the lines of:
Please use the various Facebook tags on Stack Overflow for asking detailed technical questions.