I'm not a warmonger, and I don't believe there's any chance for a full scale war, regardless what's going to hapan next. but I think it's time to give kim jong-il a decent dress-down, such as make serious attempt on his life, like Reagan did on Khadaffi, some thugs are cowards, once they realise that their own lives are in danger, they'll start to behave.
north korea doesn't have the capacity to start a war, south korea doesn't want to change the state quo, things will soon back to normal.
I think you have underestimate Kim. He came from a line of hardliner, he is crazy in a certain way... but he is not stupid... in fact he is quite a genius, playing among the great powers - China, US, Russia and Japan.
He know how to keep himself alive, that is for sure, or he would already have died multiple times. Plus I do not believe any military action is feasible on NK unless, you want to simply anniliate the entire nation fast, or you will be fighting guerilla warfare for a long period of time which would mean massive casualty.
So I think we can quit all these war mongering talks, punishing kim's talks and stuff like that, because it is something that will not happen.
And finally... it is all spectaculation that NK had hit SK's ship and sink it. No solid evidence pointed to NK... even if debris of a torpedo was found, it would be up expert to link it to NK and unless that link is found and establish, no one can say for sure it is NK who is the culprit.