Perceptron is a rule-weighting algorithm based on neural networks ("perceptrons") instead of ["GeneticAlgorithm"]s. It may replace the GA in the RescoringProcess, or maybe it already has. Really, I'm creating this page because I don't really know how the perceptron algorithm fits into the rest of SpamAssassin and I'm hoping that someone who does will fill in the details.
Some info may be found at [http://www.spamassassin.org/full/3.0.x/dist/masses/README.perceptron masses/README.perceptron].