Google has recently started to roll out algorithmic changes designed to tackle hacked spam in their search results. A large amount of legitimate sites have been hacked by spammers who engage in abusive tactics like malware downloads, promotion of traffic to low quality sites, port, and marketing of counterfeit goods or illegal pharmaceutical drugs.
According to Google, website owners who fail to implement standard best practices for security can leave their website to be easily hacked. Sites from governmental, universities, small businesses, restaurants, hobby organizations etc are all targets.
Google: We are aggressively targeting hacked spam in order to protect users and webmasters.