Well, Mark...
They actually found a comet fragment on an approach course and know where and when it's going to hit - so everybody's quitely been relocating.
But being as how the general public has been so damn cheap and unhelpful over the last couple of years, they decided that it really wasn't worth telling them about it right away - think of it as kind of helping Darwin along, improving the intelligence of the species...
My guess is that you haven't heard...
ep
:P)