We have decided we are no longer willing to continue censoring our results on Google.cn, and so over the next few weeks we will be discussing with the Chinese government the basis on which we could operate an unfiltered search engine within the law, if at all. We recognize that this may well mean having to shut down Google.cn, and potentially our offices in China.

Read more on Google blog.
Everything seems originated by cyber attacks trying to access Gmail accounts of Chinese human rights activists.
I cannot read what is the real message between the line and the real reason but this seems big news.