Interesting article - NASA had a small experiment on three of the Apollo lunar landing mission experiment packages that measured the buildup of dust. And they never looked at the data and thought they lost the data because the tapes were gone, but it turns out that the principal scientist kept a set of backup tapes.
Turns out, according to now-published analysis of the data, that the dust builds up incredibly slowly, but 10x faster than the incredibly slowly that was previously thought to be the rate of buildup. The way it happens is that solar radiation knocks some electrons off some of the dust particles, so they build up a positive charge. On the dark side of the moon, the solar wind puts some electrons on the dust particles, and they get a negative charge. When the nightside meets the dayside, the charge attraction lofts the dust into the lunar sky.
Seriously. At least that's what I think the article says.