What is going on with the Japanese nuclear reactor is certainly bad news, but it is by no means a major catastrophe. Loss of life and damage caused by the actual earthquake and tsunami is far, far, far greater even under a worst-case scenario (and the most likely scenario is essentially zero effect on Japanese people and minimal effect on even the workers themselves).
It is very distressing to me that Americans so fear-oriented about nuclear matters. The greatest risk of this incident to humans and the environment has nothing to do with the nuclear incident itself but rather the higher use of coal, petroleum, and other dirty energy sources that nuclear power could otherwise displace. For example, coal electrical generation kills thousands of people per year via pollution, and the economic cost is estimated at $500 billion dollars [source].
(The situation w.r.t. terrorism is very similar -- e.g., the TSA has unquestionably caused a net loss of life because they make people more likely to drive, which is riskier than flying, and their procedures do little to actually protect us from terrorism.)
Anyway, if you're interested in facts, not fear, about the nuclear incident (which I hope you are), here are a couple of sources which I am finding extremely helpful and easy to understand. They both have RSS feeds.