Apple s implementation of a semi-new set of technologies collectively known as Gatekeeper in the upcoming Mountain Lion release of Mac OS X is set to give users better control of the security of the machines. The Gatekeeper system will enable users to decide which apps they trust and then prevent pretty much anything else from running. Apple has been criticized roundly by security researchers, users and others for a perceived lack of commitment to security, especially on the Mac platform. Starting on March 1, all apps that come through the official Mac App Store will have to be sandboxed.
Source: https://threatpost.com/gatekeeper-bring-tight-app-controls-os-x-mountain-lion-022112/76241/