According to the Official Google China AdSense Blog , ads of Chinese AdSense publishers will open in new window starting from today. This is in respond to the overwhelming request from publishers and to improve user experience of Chinese web surfers. This is what the rest of the post said:
The Chinese market and the demands of Chinese publishers is very important to Google AdSense network. We hope to being better experience to users, more revenue to publishers and more earnings to advertisers through constant improvement of our products. By this, we could achieve four-win situation: users win, publishers win, advertisers win, Google wins.