Apple removed the previous statement "It doesn't get PC viruses" and replaced it with "It's built to be safe", and "Safeguard your data. By doing nothing" with "Safety. Built in". A comparison of the old and new messages is currently available here.
According to Sophos US senior technology consultant Graham Cluley, this is a sign that Apple is starting to take security seriously.
"I view the changes in the messages pushed out by their marketing department as some important baby-steps," he wrote in a blog entry.
"Let's hope more Apple Mac owners are also learning to take important security steps--such as installing anti-virus protection."
In addition to changing its marketing messages, Apple has released a security guide for the iPhone operating system iOS and announced in February that OS X 10.8, or Mountain Lion, would include a new feature called Gatekeeper that would restrict which applications users can install on their devices.
Cluley is not the only security expert who has urged Apple to improve its OS protection.
In a recent interview with Computerworld Australia, Kaspersky Lab co-founder Eugene Kaspersky said the company needed to extend time frames for supporting older operating systems. For example, in May this year Apple ended support for OS X 10.5, also known as Leopard, when OS X 10.7 was released.
"Apple has stopped supporting some older operating systems but there are still millions of people using these systems," he said. "It means if vulnerabilities are found, any kind of bad guys will be free to infect these machines."
Apple Australia was contacted by Computerworld Australia but declined to comment.