Ted,

They didn't "pick" sites. Their software randomly selected ip addresses and infected them. It was a trial run from a group out of China. They have the government there going crazy. Afraid this group will release a virus during the Olympics attacking all the Olympic related sites.

The Chinese government has not been able to identify the people responsible but believe they can block the next attempt. It is a matter of saving "face" for them.

It was written up in the industry ( computer security ) trades.

Pete