"One feature coming in OS X 10.8, Mountain Lion, is Gatekeeper — an enhanced security feature," announces Jim Hamm. He elaborates, "Recently, Macs have been attacked by malware, and we'll probably see more attacks in the future. Additional security protection is always welcome. Here are some comments about Gatekeeper. From AppleInsider and from Apple.com
Here Jim goes on to quote from John Gruber of DaringFireball, posted 2-16-12. "My favorite Mountain Lion feature, though, is one that hardly even has a visible interface. Apple is calling it 'Gatekeeper.' It’s a system whereby developers can sign up for free-of-charge Apple developer IDs which they can then use to cryptographically sign their applications. If an app is found to be malware, Apple can revoke that developer’s certificate, rendering the app (along with any others from the same developer) inert on any Mac where it’s been installed.
"In effect, it offers all the security benefits of the App Store, except for the process of approving apps by Apple. Users have three choices which type of apps can run on Mountain Lion:
1. Only those from the App Store
2. Only those from the App Store or which are signed by a developer ID
3. Any app, whether signed or unsigned
The default for this setting is, I say, exactly right: the one in the middle, disallowing only unsigned apps. This default setting benefits users by increasing practical security, and also benefits developers, preserving the freedom to ship whatever software they want for the Mac, with no approval process.
"Call me nuts, but that’s one feature I hope will someday go in the other direction — from OS X to iOS."