This just in, from Scientific American:

[T]he waste produced by coal plants is actually more radioactive than that generated by their nuclear counterparts. In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy.

At issue is coal's content of uranium and thorium, both radioactive elements. They occur in such trace amounts in natural, or "whole," coal that they aren't a problem. But when coal is burned into fly ash, uranium and thorium are concentrated at up to 10 times their original levels. Fly ash uranium sometimes leaches into the soil and water surrounding a coal plant, affecting cropland and, in turn, food . . . [E]stimated radiation doses ingested by people living near the coal plants were equal to or higher than doses for people living around the nuclear facilities.

Not that the risk of radiation from either coal plants or nuclear power plants appears to be significant for those living nearby.