writes "The Chinese government has been accused of backing the APT1 hacking group, which appears to be part of the Chinese People's Liberation Army (PLA), according to the security firm which worked with the New York Times when it fell victim to an attack. The firm, Mandiant, says that APT1 is government sponsored, and seems to operate from the same location as PLA Unit 61398."
Unsurprisingly, this claim is denied by Chinese officials
. You can read the report itself online
(PDF), or skim the highlights