I have had people raise concern about the new PCI Compliance laws as to whether zencart is considered PCI compliant. So... I checked around and had one of the abuse and security analysts from where my dedicated server is hosted and here was his response:

Your business is PCI compliant as long as you are not storing Track 1 CC data which consists of the full CC number, name, expiration date. As long as this information is not being stored, you are fine. Using a payment gateway to put in payment information allows you to avoid PCI compliance as this is passed on to the payment gateway.