"On the other end of the spectrum, the ideologists use the Internet to convey their message using Web hacking. Their main vehicle is defacing web sites."...
"When further analyzing defacement incidents, we found that the majority were of a political nature, targeting political parties, candidates and government departments, often with a very specific message related to a campaign. Others have a cultural aspect, mainly Islamic hackers defacing western web sites."
The report also looks at who is targeted most often for web defacements:
"Government is a prime target due to ideological reasons, while universities are more open than other organizations. These statistics, however, are biased, to a degree, as the public disclosure requirements of government and other public organizations are much broader than those of commercial organizations..."
"On the commercial side, Internet-related organizations top the list. This group includes retail shops, comprising mostly e-commerce sites, media companies and pure internet services such as search engines and service providers."
THE WEB HACKING INCIDENTS DATABASE 2008