Implemented as a Top10 list per org as "Oldest open Gerrit changesets by organization without code review" on http://korma.wmflabs.org/browser/scr-backlog.html
http://korma.wmflabs.org/browser/scr.html shows "Age of open changesets by affilation (monthly snapshot)". It would be very useful to offer a backlog of oldest opened changesets by affiliation, so people could act on those metrics.
For instance, right now there is a single changeset from Wikia spoiling the whole graph. :) Or in the Gerrit Cleanup Day we had a goal about cleaning the queue of open changesets submitted by volunteers, and a backlog by affiliation would have been useful.