Well, I feel about the same on North Korea as I do on Iraq which is simply that if they ever tried something really stupid, they could get no real world support and would end up being crushed, even by former allies like China, who don't want to disappoint the United States. Therefore, they're not a threat in any capacity. The problem that exists in North Korea and not Iraq is the fact that North Korea doesn't oppress their people to the extent of Iraq, and the North Koreans are very seriously involved in what they believe in -- the problem is that they often believe in the 'Death to America' philosophy so popular to the axis of evil. The people of North Korea are hostile enough and resourceful enough to do some damage of their own, if maybe fueled slightly by their (fairly popular) government. In Iraq's case, on the other hand, the people are oppressed, they're laid back, and they have no violent anti-American demonstrations or riots because the government already conveys the point that the country is anti-American and doesn't need the people to push it.
Overall, North Korea definitely poses no current or immediate threat, and I think they're cleaning up their act. The next few years and The War Against Terror will tell, I suppose.