I also immediately thought of a corollary when thinking of religious blogging since that is where I spend a lot of my blogging time. I think within very conservative circles that the corollary would be, "As an online religious discussion grows longer, the probability of a comparison involving legalism or Pharisees approaches 1.”
There is also a special corner of the blogosphere where self-identified fundamentalists hang out and it has it's own corollary: "As an online discussion among fundamentalism grows longer, the probability of a comparison involving Neo-evangelicals approaches 1.”