The attack on Google was said to be a way to get access to the accounts of free rights activists, but they also attacked several other US companies. The reason must be to steal the companies' know how.
Would you be surprised if a few years from now a Chinese Google was announced and similar and maybe better products in other industries?
And I think these actions are all supported by the Chinese goverment which knows getting chinese competitors in some key fields is the only way of exponentially develop its economy.