On the subject asteroids and other near eath objects, Slashdot has the best coverage on 2004 MN4.
JPL has a nice fact sheet replete with animations. 2004 MN4 has a 1/63 chance of hitting the earth, with the damage depending on the asteroid’s composition.
Let’s focus on the real threats.
The worst case is “if the asteroid hit the wrong place at the wrong time, it could cause a giant tsunami wave or deliver a nuclear-scale blast.
Keep in mind, though, that the risk of such an event is low—much lower than, for example, earthquake generated tsunamis like the ones yesterday that killed around 7,000 people [The death toll now sadly may reach 50,000].
Though not as sexy as planetary defense, the best mitigation measure for disasters like tsunamis is still improving the quality of governance and development for poor people around the world. The United Nations Development Program released a report, Reducing Disaster Risk: A Challenge for Development, that concluded:
Most fundamental is the role of governance at all scales from the local to the global. A balance between equity and efficiency in the distribution of decisionmaking power and in making decisions will need to be kept.
Which, if you think about it, is the kind of thing that Christmas is supposed to be about in the first place. Now, back to our regularly scheduled orgy of consumerism.