The same day that asteroid 2012 DA14 is approaching close to Earth, a meteorite explosion in Russia has injured over 900 people, mostly from broken glass. The two objects are unrelated and traveled in completely different directions.
The smaller of the two objects (the one that hit Russia) is estimated to be about 10 tons and exploded about 18-32 miles above the Earth’s surface [later estimates pegged it at 10,000 tons]. The larger object is estimated to be about 130,000 tons and will pass within about 17,000 miles of the Earth (closer than our communication satellites).
Videos of the Russian event:
See Russia Today for more information about this event.
Asteroid 2012 DA14, if it were to hit the Earth, would result in the approximate equivalent of the Tunguska event in 1908 (the equivalent of 1,000 Hiroshima bombs).
In the long run, the best way to avoid asteroid damage to the Earth (even possible extinction events) is to utilize the asteroids as building materials for space settlements, solar power satellites, etc.!
See the NSS website Planetary Defense Library.