Any merchant should protect their point-of-sale environment to the same level as the rest of their cardholder data environment. Maybe even a higher level since the POS's are more vulnerable to physical threats.
Are My Point-of-Sale Boxes in Scope Too?
Andi Baritchi 27000216AA email@example.com Tags:  dss pci malware anti-virus appliance usb point-of-sale 786 Visits
If they see cardholder data - YES. Check out The TJX Effect and Keeping Point-of-Sale Equipment Secure for the rationale behind this.