...or at least that's the claim. Whether or not North Korea actually detonated a test device or we are merely hearing the continued ravings of Kim Jong Il, I don't know. (The evidence suggests that something happened)
Even if North Korea has nuclear arms, I'm not sure it means a whole lot on the world stage. Kim Jong Il is, as far as anyone can tell, a quasi paranoid loon whose focus appears to be on stirring things up, rather than any kind of coherent plan.
About the only thing we know about North Korea is that the country can't even feed itself, and most of its citizens depend on international aid for food. That probably means that most of the country's resources are bound up in military programs of some sort or another, but at the same time, it's pretty apparent that the country hasn't got a whole lot of anything to bargain with. Certainly, without nuclear capabilities, they are pretty well hemmed in by powers that aren't overly impressed with the current ruling bunch of loons.
Do they pose any real threat outside of the Asian region? No. Even their "long range" missiles are unlikely to reach across the ocean today. Does the fact that they now publicly claim they have nuclear weapons change anything. Probably not. We have no idea how much of the old soviet-era nukes found their way into North Korean hands, and I suspect that there's a few that they've had 'in reserve' for a long time.
I fully expect to hear lots of the "A madman has nukes" line for the next little while - of course the people wringing their hands over that will be conveniently ignoring that other madmen have been running around starting wars - and they have much bigger arsenals than Pyongyang will ever achieve.