From the Los Angeles Times (free registration required):
Imagine what would have happened if during the 1980s an American communications company had provided information that allowed the South African government to track down and imprison an anti-apartheid activist. That is pretty much the moral equivalent of what Yahoo has just done in China in the case of journalist Shi Tao. And the California-based Web giant deserves the same kind of public opprobrium that would have fallen on any Western firm that dared to publicly cooperate with the enforcers of apartheid.