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 firstname.lastname@example.org Tags:  pci dss malware appliance anti-virus point-of-sale usb 757 Visits
If they see cardholder data - YES. Check out The TJX Effect and Keeping Point-of-Sale Equipment Secure for the rationale behind this.