Police corruption is a major source of public anger in China. In the last few years, people have increasingly held mass (thousands, to over 10,000 people) demonstrations, some of which have turned violent, against police misconduct (corruption, torture and murder of suspects and general mistreatment of prisoners.) The corruption affects the general population, as it generally manifests itself in police demanding bribes, and arresting those who do not comply, or otherwise annoy the police. What worries the government the most is that many Chinese are willing to fight back when the police show up. If the cops cannot coerce and control the population, the government cannot be assured of surviving popular uprisings.
Taiwan has agreed to send military officers to a conference in Hawaii this August, which will also be attended by Chinese military officers. This will be the first time in 60 years that Chinese and Taiwanese (or, to put it another way, Communist and Nationalist) officers have met. Back then, they met to arrange the surrender of Nationalist forces on the mainland. Those Nationalist troops who did not surrender fled to Taiwan and fought off Communist attempts to subdue this last bastion of Nationalist power.
March 29, 2009: Tibetan exile groups had their computer networks checked for Chinese interference, and discovered a widespread hacking effort that extended to governments, and NGOs (non-governmental organizations). Over a thousand computers were found to be secretly taken over by what was dubbed the "Ghost Net." The controllers of this network were based in China, and the investigators uncovered incidents where Chinese police and officials used information that could only have been gathered by Ghost Net.. The Chinese government denied any knowledge or involvement. Over the last decade, incidents like Ghost Net have been occurring with increasing frequency.
March 26, 2009: A new U.S. Department of Defense report on Chinese military power asserts that China is modernizing its military power and creating a navy and air force that can project military power much farther. The U.S. believes this is so China can enforce territorial claims, which for decades have been merely rhetorical, by using a convincing threat of military force. China denied all this, and insisted their military buildup was strictly for defensive purposes, and for peacekeeping missions around the world. China's neighbors, however, agree with the American assessment.
March 23, 2009: China blocked access (for all Chinese Internet users) to YouTube, because of the presence of videos favorable to the Dali Lama and Tibetan independence. A quarter of the world's billion Internet users are in China, and the government is increasingly nervous of the power of this largely uncontrolled media. Chinese media have been cowed into self-censorship, and shutting down access to YouTube is how China persuades foreign media to obey and self-censor. However, there is resistance in the West to this censorship, and an increasing number of Chinese are getting annoyed with it as well. This bothers the government, which is basically a police state. You can't run a proper police state if you don't control the media, and the Internet is proving uncontrollable.