I was just about to post to AskHN about how much data these social network behemoths can garner from unposted data, i.e., I write something into my status box or a comment like "fuck the police," then delete without posting, is that data gathered and mined? My gut and brain say yes, because it's easily possible to gather it and with the little bit of research I found no evidence that really shows one way or another what happens behind closed doors at these mega companies.