I knew this was going on. I just hadn't really considered the implications. I know a lot of folks here will say, "I don't use facebook." But a lot of people do, and few businesses can afford to ignore it. Just imagine the impact these sites could have on an election with some of their "experiments."
No, the real problem is that OKCupid and Facebook may take action based on the results of their research. In both cases, the companies say they're experimenting in order to improve their service.