Update 3. MasterCard is back, and Anonymous (those behind Operation Payback) have issues a press release. Update 2: The group (Operation Payback) credited with bringing down both MasterCard.com and Visa.com has had its Facebook Page removed for violating terms of service. It's Twitter account was also suspended. Update: Visa.com is now down as well. MasterCard.com is still down. (As of 4:30pm Eastern)