Long story short... Google earned a license to operate in China in 2007 on the condition they would censor the search results. Fast forward to 2009, Google was part of a Chinese government hack, which compromised Google's security, got Google mad and Google said they would leave China. Google then started automatically redirecting Google.CN (Google China) to Google.co.hk (Google Hong Kong), which China didn't like. So Google set up a deceptive manual redirect where users were tricked into clicking on a picture of a search box and then redirected to Google Hong Kong, which is technically a manual redirect.
China fell for it or simply wants Google in China and gave in. I don't know.
Forum discussion at Google Blogoscoped Forums.