Terry just sent me the link to a Tokyo Radiation Levels page on Metropolis magazine's website. It looks like a very handy way for anybody following this dicey situation to keep things in perspective.
"Due to concerns about radiation in Tokyo from a number of our readers, Metropolis will publish daily radiation levels (sometimes multiple times daily if relevant). This is a log of background radiation levels in Tokyo from March 15 2011. Measurements will be taken daily at different times. Levels are measured in micro-Roentgens and micro-Sieverts using using a Polimaster PM1703M Scintillator and S.E International Radalert 100 Geiger counter respectively."
"We are not qualified experts in the field of nuclear science and nuclear medicine. Metropolis owns a Geiger counter and we are just giving a daily reading of exactly what we see on the screen of the Geiger counter. Geiger counter readings are taken outside, in an open area after the device has had 2 minutes to get an average reading of the background radiation level."
I like the "what does this compare to?" section, and the "what do the units mean?"
Bottom line: Levels detected over the last several days are "safe"