If you are aware of the whole story about the wikileaks and opback you would have know that the hackers or attackers of Visa, Mastercard have written several emails to the Mashable (The social media news blog) about their attacks for example look into to example below:
Mashable received an e-mail from a person claiming to be affiliated with Operation Payback saying:
“Make sure everyone knows that we are not 4CHAN. 4CHAN has nothing to do with this.
We are currently attacking Paypal.
Target api.paypal.com port 443 and it seems sluggish at this time.
Again, we are not 4CHAN, we are an anonymous involuntary group called AnonOps
With the Amazon attack, they are simply toooo big for us right now. Maybe at a later time we can try again with them.”
And now the latest news is that the attackers have brought down Mashable.com itself.