How does this actually get implemented in code?
All of the "ZD strategies" are described by 4-tuples of probabilities: the probabilities of cooperation given the outcome of the previous turn, which can be one of (CC, CD, DC, DD). In comments to the previous post I calculated two examples, and the paper contains the general formulas in equations [8] and [12].
Less Wrong had a Prisoner's Dilemma contest some time back, whose results I've forgotten. Perhaps it should be rerun with William H. Press & Freeman Dyson's proposed extortionate strategies.
I hope Pinker gives a response at Edge.org, since P.D played a significant role his book "The Better Angels of Our Nature" as a source of morality embedded in the nature of logic/reality.
Hat-tip to Marginal Revolution.