Tokyo Electric Power Co. (TEPCO)—the company that runs the Fukushima nuclear plants—says that 70% of the fuel rods have been damaged on the reactor 1 and 33% have been damaged on reactor 2. "The reactors' cores are believed to have partially melted" says the Japanese news agency Kyodo. Sadly, this confirms the judgement of international experts, who criticized Japan for underplaying the crisis.
I'm not sure this is really any worse than they've been saying for at least a day. They said a day or two ago that they were assuming that at least some portions of the cores for two of the units had melted. The real problemw ould be if the containment failed. So far, I haven't see any sign of that, though it's tough to sift the accurate details out of the reports that all seem to hit the different news organizations at different times.