Apophosis revised - by a school kid!
The article is a little half-baked and garbled, but basically it says that our own geostationary satellites are enough of a flea-swat to slow down a whole asteroid and throw the calculations out...
http://www.theage.com.au/news/world/brock-shockb-schoolboy-corrects-nasa-killer-asteroid-maths/2008/04/16/1208025230056.html
"what did you do for your school project today, son?"
"Oh not much Mum, I just predicted the end of the world..."