According to der Spiegel, a French model calculates that the Fukushima nuclear power plant in Japan has already released one-tenth of the amount of radiation that was released at Chernobyl in 1986 -- and that was as of last Tuesday.
This site says that the total radiation release from Chernobyl was 100 megaCuries, and that the total release from Three Mile Island was 15 Curies. Thus Chernobyl = 7M x TMI, and if the French model is correct Fukushima = 700,000 x TMI.
We have been very lucky that no one lives immediately east of Japan. (But I wouldn't want to be immediately west of Fukushima either.)