Comment group takes responsibility (Score 5, Informative) 82
A group calling themselves AntiLeaks has taken responsibility for the attacks.
Here are a couple of stories on a german tech site about the group. You can translate it into german.
http://www.gulli.com/news/19466-antileaks-ddos-angriffe-als-protest-gegen-wikileaks-2012-08-08
http://www.gulli.com/news/19456-ddos-angriffe-legen-wikileaks-lahm-2012-08-07