Update 1615 pst: Visa seems to be winning the battle in the US, at the expense of their Europa websites. Anon ops back up on Twitter as @Op_Payback. end
According to an Anonymous-related Twitter account, visa.com succumbed to the voluntary botnet LOIC (Low Orbit Ion Cannon) within 16 minutes of becoming the new target of "Operation Payback".
It is unclear whether Visa payment processing is being affected, but MasterCard confirmed that its payment processing server was crippled after overnight Anonymous attacks.
Twitter recently suspended the @Anonops account. When the LOIC target became MasterCard, a graphic was circulated indicating that Twitter may also be targeted.
As of this morning, over 1700 computers were connected to the LOIC hivemind (the targeting source). The PayPal blog has been an intermittent target over the past few days, but rumors indicate Anonymous will target the PayPal main site if the hivemind connections reach 5,000.