While I find it pretty murky to figure out exactly what's happening in Japan, it seems that the radiation released is still much less than Chernobyl. Maybe the radiation could get as bad as Chernobyl, maybe not, but it definitely won't result in as many lives lost. Compare that to the million people annually who die from from fine particle emissions, in large part from fossil fuels, and it's no contest. Meanwhile, Germany and China partially suspend their nuclear programs while their coal plants chug away, actions that don't help safety unless they later plan to make up for lost time.
So I'll stand by what I wrote in 2005, that nuclear power is too safe relative to fossil fuel competitors. I suppose you could argue it's worthwhile to make the worst 10% safer while making new plants less safe than otherwise planned, but that wouldn't change the analysis. I also suppose it's less safe than the industrial accidents from renewable power (don't really know the answer to that), but that's not the binary choice we have in our current system.
I tried to figure out what could change my mind on safety, and it would have to be getting a lot of Chernobyls. However, nuclear power could be ruled out with only a few Chernobyls because they have the effect of making significant land areas uninhabitable, an adverse economic effect. Nuclear power is just too expensive to be more than a minor contributor to climate solutions, unless we go along with the conservative push for giant subsidies for nukes. Maybe we need to, but that doesn't make it optimal.
One other point: Matt notices that nuclear power is only safe due to governmental regulation, and still conservatives love it.
And another: this BBC article points to a proposal to put a nuclear waste depository in the already-uninhabitable Chernobyl area. It doesn't make much sense in the thousands of years that we'd theoretically need to store it, but it does make sense for the actual century or two that's needed, and afterwards a much more advanced technological society can figure out a better solution.