"The Department of Homeland Security is aware of the recent cyber intrusion to Sony's PlayStation Network and Qriocity music service," DHS spokesman Chris Ortman stated, "DHS' US Computer Emergency Readiness Team (CERT) is working with law enforcement, international partners, and Sony to assess the situation."
Unlike the Subcommittee on Commerce, Manufacturing, and Trade, the US Homeland Security is getting involved in a more forensic way, since one of its functions is to investigate cyber-terrorism. As Patrick Burke, a subcontractor hired by DHS, put it, "There's an adversary that we're trying to defeat." DHS is less interested in assigning blame to Sony than finding out just what happened.
The FBI is also reportedly involved. FBI Special Agent Darrell Foxworth said in a statement: "The FBI is aware of the reports concerning the alleged intrusion into the Sony online game server and we have been in contact with Sony concerning this matter... We are presently reviewing the available information in an effort to determine the facts and circumstances concerning this alleged criminal activity."