For those who didn't hear, there has been an arrest of two Mexican citizens in Texas who were using stolen credit card numbers to purchase goods - and that the case possibly leads back to the Target data compromise.
Quite honestly, with today's computer security suites, there is almost no excuse for a static configured system such as a Point of Sale terminal to ever be infected by a virus. With proper implementation of application whitelisting a system can be protected from even unknown malware.
However, the Payment Card Industry Data Security Standard (PCI-DSS) only requires basic anti-virus coverage to protect against "known" malware, as well as a (network-based) firewall.
