Hi Rubin,
I read the Phab ticket and feel your pain. A little bit of good news is that some data is already available for ru.wikimedia, in a project we call
Vital Signs. You can select different metrics from the bar at the top and see the definitions of each metric by clicking on the graph title. To gather these statistics, we use two publicly available sources of information:
labsdb: a replica of the production database with private information stripped out
pageview stats: compiled in our Hadoop cluster (the definition of pageview is currently changing and we'll have fresh new data soon, with an API as well).
I know this is most likely not enough, at least not as much as piwik would give you. We have been talking about setting up a piwik instance here so we can host the data and abide by our privacy policy. This discussion is ongoing with legal, but there are many people requesting piwik and I am optimistic it will go forward slowly. As for setting up a separate piwik instance and allowing our site to talk to it, I am pretty sure that's against our privacy policy, as the
last comment in the Phab ticket says.