An unintended side-effect of the new scoring scheme, which averages over points on-the-line between question opening and closing, was that putting in a prediction right before closing makes hardly any effect. This is unfortunately both because it makes things less fun and exciting, and also because the community prediction at closing time is probably the most useful piece of information created by the community on each question, and should be optimized.
Thus in a slight tweak to the scoring scheme, we’ve now added extra weight to your last prediction; this makes the current scheme a hybrid between the original scheme (where all the weight was on the final prediction before closing) and the time-averaged scheme. The weighting is roughly 2/3 for the time-averaged part, 1/3 for the final prediction.
While the means to a best score is still to predict accurately, early, and often, this will hopefully help predictors better allocate their efforts.