Tsunamis, Asteroids, and Not Behaving Like an Ostrich

One of the most tragic aspects of the Indian Ocean tsunami is that many lives could have been saved if there had been a warning system. The cost of such a system, a few million dollars, would be negligeable in regard of the devastation of such events, rare as they are, with some estimates putting the death toll above 50,000.
One irrational part of human nature seems to take precautionary measures only after disaster has struck. Though it was another cry-wolf event, the reports about 2004 MN4 a couple of days ago are a darkly ominous coincidence.
Given that even a rock the size of your bed has the explosive energy of tactical nuke (and indeed more than thirty such stones strike the Earth each year; try different sizes for yourself), I hope we will have an efficient warning system before the cataclysm happens.