Officials from the US and South Korean governments announced that the Kwangmyŏngsŏng-2 satellite failed to reach orbit, and this was later validated by an official statement by the Russian Space Control who could not detect the clamined satellite in orbit. Russia however does intend to help North Korea launch future satellites according to this ITAR-TASS aritcle.
Well, too bad for North Korea, but in any case, thanks to Analytical Graphics, we have this great ring-side seat view of what the action would have looked like!
Note the first stage falling in the waters before Japan's land territories, and the second stage falling in the ocean long after passing Japanese territory. According to the wikipedia article the first stage impact point was within Japan's exclusive economic zone but outside its territorial waters.
It's a pity that in this verison we don't see one of those US missiles coming up to intercept it ;-)
The claimed North Korean satellite is absent from the United Nations Online Index of Objected Launched into Outer Space however North Korea did complete its accession to the Convention on the Registration of Objects Launched into Outer Space.