This episode is a few weeks old, but I don't think the information or view points go stale. There were outbursts of surprise when it Facebook published their paper about potentially being able to manipulate people's emotions by adjusting the "mood" on their Facebook timelines.
Christian Rudder of OkCupid talks us through how using measurable testing on real users means a better experience for all users of OkCupid.
My take? It seems naive to believe that this kind of testing isn't happening on every service we visit. Maybe especially so on services where our attention is ostensibly the "product".