In the New York Times, Tina Rosenberg writes:
It was the force of capitalist profits, not Communist law, that compelled Yahoo to hand over Shi Tao and its unapologetic response seems devised to ingratiate Yahoo further with Beijing. Last month, Yahoo spent a billion dollars to buy a 40 percent share of Alibaba.com, China’s largest e-commerce company. It was the single largest foreign investment in China’s Internet sector, and like everything else in China, it would not have happened without the good will of the party.
The Chinese market is so delicious that companies will do almost anything to get in and stay there.
See also editorials in the Washington Post and the Toledo Blade on this topic.