Apparently this group is behind it. Also attacked WoW and twitch servers.. https://twitter.com/ukdrillas
Part of the liability should be shared with the people owning the compromised machines these crazies are using for their attacks, otherwise attacks like these will never stop as long as enough free “ammunition” is being left around by incompetent people who can’t be bothered to secure & monitor their systems properly. Edit: in reply to some of the (valid) counter-arguments, I'd like to say that there are indeed many…
People also have a very limited view on what's happening on their phones, too. What if the rights to the source and distribution of a free closed-source app is purchased by someone that's going to modify it to include all users in their botnet? It's not like you can monitor what kind of traffic your phone apps send out.