at first i would have dismissed pepsi's theory out of hand but a few things make me want to agree with him.
1. If it were some individual hacker who got burned/just wants to show off, we'd have seen someone taking responsibility. "OMG I AM (insert H4ck3r username here) and I am leet!"  If it were anonymous we'd have seen tons of tweets about it already, but i agree with pepsi, everything ive seen from anonymous points to them being on our side.  The only ppl who would want to remain a mystery would be a competitor/govt just trying to bring down bitcoin businesses.

2. The strength of the attack. The first ddos strike was handled by cloudflare no problem while this one brought the entire isp down.  The site was moved to a data center that specializes in handling ddos and yet still is being taken down/vulnerable.  Thats a ton of resources/infected computers/MONEY.  this points to government interference, maybe not our normal villains the US govt but say, the government of cyprus. 

  It could also be an elaborate plan to bring the price of bitcoin down, since everyone knows that sealswithclubs.eu owns the bitcoin world, it would stand to reason that if that site went down the price of bitcoin would go down with it, since degenerate gamblers don't have a reason for buying them.  feel free to flame me for stating the obvious.

the truth is we can't really know and theres only a small chance we'll find out. but since i cant get on the site and gamble atm its fun to speculate!