Actually I have to wonder what would happen if it hit the moon. It might just add another crater, but I'd almost worry about splash damage, as it were.
It's such a small rock. It's not going to kick up anything off the moon that is big enough that could be a threat to Earth.
It'd wipe that smug face off of the moon. Actually, I wonder if it were the right composition if it'd tweak the moon's orbit. Hmmm.
APOD says it would cause a "city-sized crater' and magnitude 7 earthquake. http://apod.nasa.gov/apod/ap111109.html NASA: http://www.nasa.gov/mission_pages/asteroids/news/yu55-20111108.html