Part of the problem has to do with language. All the reports are coming out in Japanese and being translated into english. Communicating nuances across languages is very difficult.

There is also the general imprecision of the terminology independent of the language used. I've seen 'meltdown' used to describe everything from small parts of the core overheating because they were immersed in water, to the entirely theoretical and never seen China Syndrome. There are clearly melt downs and meltdowns. One is an accident that might be recovered from with an overhaul. The other is an OMG ... feet-don't-fail-me-now event.

The best reports seem to be that the hydrogen explosion at unit one blew the weather cladding off the upper, unarmored, non-containment, portion of the building. It didn't rip open the containment or catastrophically tear apart the controls or piping. It may have caused or made small leaks worse. Certainly didn't do anyone any good. At least one man, the gantry crane operator who remained at his duty station, died.

Last word I heard was unit one and three were having problems cooling the reactor cores, the core/s have been damaged because water levels dropped and portions of the cores were exposed but any damage happened after the reactor control rods were driven home to shut down the reaction. The problem is that the reactors are still hot and require active circulation of water to prevent boiling off the water and exposing the cores. This was lost when the diesel generators were damaged by the tsunami.

The Japanese engineers have started injecting seawater and intend to add boric acid to further moderate any nuclear reaction.

Several sources are claiming, and this is the part subject to revision, that core temperatures are still abnormally high but moderating or coming down.