I vote for "Angry Kid." Most likely someone just showing off or testing out the power on their newly bought booter from Hackforums. No government would ever bother attacking a website as small as Bitcointalk (well unless something was to happen between them and theymos.) Since it was a few hours long, I wouldn't say it was some random person though since the amount of resources or the price required for a three hour running attack wouldn't be too cheap. Maybe someone with a vendetta against Bitcoin?