The hottest action will be up in the sky: This space rock (which we'll call YU55 from here on out) is about a quarter-mile (400 meters) wide, which makes it wider than an aircraft carrier. It's due to zoom past us at 30,000 mph (50,000 kilometers per hour) at a minimum distance of 198,000 miles (319,000 kilometers) at 6:28 p.m. ET. That would bring it just within the orbit of the moon. But don't worry: YU55 is on course to miss the moon as well as Earth, and even if it did hit the lunar surface, the only thing that'd happen would be a fantastic fireworks show."

[link to cosmiclog.msnbc.msn.com]

I don't know how correct that sounds .. but it is msm ..
Talks more about if it hit the earth .. but so far on track not to .. sounds a lil doubtful .. for being so sure it's on track?!