Gatekeeper isn't the most obvious feature of the new OS X Mountain Lion system that you probably downloaded and installed yesterday, but it might be one of the most important. Gatekeeper essentially oversees a list of verified developers who have applied for and received a Developer ID from Apple.
It also allows you to specify whether your Mac will install apps only from the App Store, from the App Store and this list, or from anywhere you want. If you choose the Mac App Store only, you'll be able to make sure that everything you install has gone through Apple's approval process, which is about as protected from malware as you can get.
When you
