In a different incident, Google was alleged to have helped the Indian government build a case against a user who had "posted insulting images of Chhatrapati Shiva" on its social networking site, Orkut, by supplying an IP address. The story first became newsworthy not solely for Google's involvement, but because the address was later mapped to the wrong person, leading to the arrest of an innocent man (tinyurl.com/yu53b7).
What these situations have in common is that a corporation was a ready source of data. And as search engines and social networks collect more and more user data for business purposes, governments will find that data more and more useful for their investigatory purposes.
Further, as a person's stored data profile grows to include items such as group memberships, purchases and a list of friends, it forms a very tempting target for governments to try to mine for suspected criminal contacts. This concept is of course not new, with traffic analysis (of phone calls or data) being an ancient intelligence technique. But corporations are now essentially volunteering to collect all the information, put it in a readily searchable package and then perform all the analytical work. This is done because it's useful for advertising and marketing applications. Unfortunately, all of this social network material can easily be repurposed for malignant uses.
Search engine companies are understandably reluctant to confront these issues. They make predictable statements about needing to obey local laws and the benefits of their products. And the one-way broadcast aspects of blogs provides an ideal vehicle for corporations to disseminate public relations snow jobs while pretending to have a concerned human face. It is only when there is a scandal prompting media coverage, or even hearings focused on human rights, that the inevitable evasive statements might be examined sceptically.
Privacy advocates will need to keep unearthing incidents, perhaps from police reports or government files. For activists in countries where there is a freedom of information act, requests directed at police investigations might turn up examples of various stored data being used to identify crime suspects. Countries which have strong privacy laws and data protection safeguards could attempt to force an accounting of problematic uses of personal data, under the theory that data about their own citizens would be at risk of being revealed to repressive governments.
Note that while it's a common recommendation to use technical means to protect one's privacy (such as the "Tor" anonymity system, at torproject.org), such measures are frequently not workable for any but the most knowledgeable and dedicated people. They are often inconvenient and shift a burden on to citizens to be constantly on guard, as opposed to not requiring such guarding in the first place. Using privacy/anonymity programs is good advice, but in overall terms, a bad solution.
Yahoo and Google's troubles are probably just the start of what will be another long battle in the war over corporations as agents of control. Left to their own devices, such companies are driven to store as much data as possible for as long as is practical.
We cannot expect that having large warehouses of data on individuals will be free from unintended consequences, especially when there are incentives to try to build highly detailed models of everyone's lives. The price of total personalisation is total surveillance.