From Taipei Times

The signal of a government-run television station in southern China was hijacked by alleged hackers who used the frequencies to broadcast anti-government content, press reports said yesterday...during the blackout, anti-government images lasting up to 40 seconds appeared on television screens in Guangzhou, the provincial capital of China's economically booming region of Guangdong, the report said.

If memory serves me right, there have been numerous incidents of people hacking roadside information displays in the past but they usually carried humorous messages and insults. Hacking a TV channel in China to push Anti-Government messages is pretty hardcore.