PSN is down, apparently after being DDOSed.

PSN is offline at the time of writing, apparently thanks to a DDOS attack.

A group called @LizardSquad is claiming responsibility for the action.

Shacknews is reporting that Battle.net, League of Legends and Grinding Gears’ Path of Exile have also been attacked, although Hearthstone appears to be fully playable at the moment.

Update: Sony has acknowledge the issue and the FBI is investigating a bomb threat which inconvenienced SOE president John Smedley.