Well if I see more chickens with two heads and four feet and three wings, should I be worried?
Seriously though, while it is bad in Japan, I don't think there is enough radiation to be released to cause people to become ill in general. However I am sure there are those who are more susceptible to it so they dispensed potassium iodine as a precaution. I believe Japan has more nuclear reactors than the United States so this should have been seen a long time ago, but at the same time no expected the back-up generators to fail either.
I am sure Chernobyl rings in people's minds when they think of a nuclear disaster. But far as I know the actual nuclear reactor at Fukushima has not exploded only the hydrogen buildup inside the containment building. So far they have released some radioactive water, not sure how this will play out in our oceans. =/
I am sure if it truly does get as bad as Chernobyl, the world as a whole will do what they can to save human life and to take precautions against any radioactive 'bubble' that might be headed their way. I feel confident that international authorities are doing their best to get it under control and will work continuously to keep it under control once they do. Is it possible that Fukushima could be shut down permanently?