Though I haven't yet begun the semester, this was too huge to just ignore. A second nuclear test by North Korea should show them to be a real nuclear power (though the results are still awaiting confirmation).
If North Korea is a standard power, then nuclear weapons on the peninsula could actually be beneficial. If it convinced North Korea that it wasn't going to be subject to attack at any moment by the US, then perhaps it would be willing to better participate in the global arena, or at least stop threatening its southern neighbor.
However, we have no assurances that North Korea is any old country. It is the most opaque country in the world, and its constant belligerence does nothing to soothe anyone. Moreover, the lack of forewarning for this test further shows this; there was no effort to warn the world or make it comfortable with the threat.
Overall, though, unless it is proven to have been a substantial improvement over the last one, it probably won't be much of a game changer. Everyone already knows that North Korea has nuclear weapons; everyone knows they can't really get them reliably past Japan; and everyone knows it would still be suicidal to attack either South Korea or Japan.