From playstation lifestyle:
After claiming that Sony’s lawsuit against George Hotz et al was an attack on free speech, hacking collective Anonymous declared war on Sony. Hoping to seek revenge on the company, Anonymous warned that Sony would soon suffer for their actions. Now, Sony.com and PlayStation.com has fallen to the hackers, with more sites promised to follow.
Anonymous, the group of hackers that threatened war on Sony, and then subsequently brought down several Sony sites, as well as the PSN to some degree, have released a video promising that the attacks will continue.