Whilst I am fully aware of the fact that the events at Fukushima may lead to a rapid deterioration of the situation - right now there is no reason to worry in Tokyo:
Tokyo radiation levels are 10 times the normal value. Scary scary, eh?
But what does it mean in reality?
0.809 micro sieverts/hour were recorded in central Tokyo at 10.00 a.m. local time on the 15th.
Now how does that relate to other sources of radiation?
How about an hour of flight time?: Gives you about 5.5 micro sieverts
Eating a banana? Gives you 0.1 micro sieverts ...
you get my drift?
there is no reason to worry (not yet, anyways)