After doing a lot of research and visiting WMF for a week, I created a QA/testing project page here: http://www.mediawiki.org/wiki/QA/testing
tl;dr: it is early days yet and lots of details to be worked out, but I have a picture in place of an integrated, valuable QA/testing structure and process that revolves around Jenkins and the labs cluster wikis. In the long run this should provide a reliable way to involve the global software testing community in WMF features testing, as well as involve WMF tech people in valuable testing activities.
Comments and criticism most welcome!
-Chris