Iwate and Miyagi Prefectures appear to have been hit the hardest. Not a lot of information is available at this time, but judging by how this quake is as strong as the one that hit Niigata last year, there will probably be buildings damaged and people injured or killed. (The closest nuclear plants to the earthquake-hit area have already reported in that they have suffered no damage.)
Update: At least 3 people are dead and 167 people injured at the time of this update. 10 people have been reported missing (may include a group of 3 foreign English teachers and 1 Japanese person who had gone camping near Komano-yu-onsen).
There has also been a bizarre discovery: an old Black Jack manga by Tezuka Osamu had an earthquake in Tohoku around 8:00AM on June 14th of an unspecified year. [hat tip to Toru]