AFAIK the first experiment was ClickTracking for the usability
initiative in 2009-10:
We've waited for its data for years, I suppose we can assume it will
never be shared; it had some anonymization problems (aka nobody bothered
to check if there was something non-anonymized in it). It was used only
to decide that collapsing everything (even interlanguage links) on the
sidebar was a good idea:
In the current status of things, all such tracking features current and
future are – I believe – supposed to use
(this page is outdated).
In a bright future, all such data will be available for everyone via
, so I think that in this
non-mythological present nobody will bother to do work that would end
duplicating those features and only WMF people will have access to it.
If something happened to be available, you'd most likely find it on
(there doesn't seem to be anything).