Ilari told me about the formula on IRC:
[17:46] <Ilari> FractalFusion: Well, the formula is: r^(2.6-0.2*average_rating_count/rating_count)/sqrt(p). Note that average_rating_count and rating_count count each tech and entertainment rating as one rating, instead of 0.5 like movie pages). r is weighted average (not weighted average of averages).
[17:47] <Ilari> FractalFusion: If exponent is smaller than 1, it is forced to 1. If result is smaller than 5, it is forced to 5. Obsolete movies get points multiplied by 10^-6.
[17:48] <Ilari> FractalFusion: Oh, and movie author ratings are ignored for averages but not for rating counts.
[17:50] <Ilari> FractalFusion: Furthermore, stars have multiplier of 1.5, moons has 1, vault has 0.75. So the absolute maximum score per movie is about 597.
Not sure what the "bell curve distribution" was supposed to mean, but don't worry about it.