Yesterday, Google and Google.cn were blocked in China. According to Sina, a local news portal, Google was inaccessible from 17:23 to 18:45; Google said they researched the cause and couldn't find anything wrong on their end so the conclusion is that the block was by the so-called Great Firewall of China. It is not yet known if it was accidental or not.
[source: blogoscoped.com]
[source: blogoscoped.com]