The Fukushima Power Plant located in the Futuba District of Japan has sustained severe damage in the March 11 earthquake and radiation levels are rising in and around the plant following a number of explosions at the reactor units. It has been reported that radioactive steam might have escaped from the containment unit of a second reactor at the Fukushima plant forcing emergency workers to halt their efforts at keeping water on the reactors' overheated cores.
At TargetMaps you can see a real-time visual summary of radiation levels by Japanese prefecture.
Officials stressed that current radiation levels are only dangerous in and around the plant itself. The level of radiation detected 12 miles from the plant was 0.33 millisieverts per hour, as on March 16. That's the rough equivalent of three chest X-rays an hour.
An area within 12 mile radius from the stricken nuclear plant has been evacuated and people living within 12 to 20 miles has been asked to stay indoors.
Daily life in Japan, even in cities well outside the the quake zone, is increasingly disrupted by frequent blackouts. A real-time update of these blackouts is being provided by Google Japan.
Another real time map of wind pattern in Japan can be found at Weather Reports. The direction of wind flow is vital as it indicates the direction in the which leaked radiation is moving. From the map it looks like it is moving out to the open sea, which is good I suppose, unless you are worried about marine life.