When the Mac App Store launched a year ago, reactions were generally positive. Some, however, worried that Apple was moving toward the “walled garden” approach it has taken with the iOS platform. While software can be loaded onto a Mac from any source – internet download, disc, or whatever – iOS apps can only be installed via the App Store. The concern was that Apple would eventually lock down OS X in the same way.

These concerns were amplified earlier this month when Apple announced OS X Mountain Lion. One of the features of the new OS was a system called Gatekeeper. Gatekeeper is a security feature that allows users to control how software is placed on their computers. At its highest setting, Gatekeeper only allows software downloaded from the Mac App Store to be installed. The lowest setting allows installation from any source. In the middle is a setting that allows Mac App Store software, and software from developers who are part of Apple’s Developer ID program. The program allows developers to sign their apps in such a way that Gatekeeper will allow them to be installed on users’ machines.

With the launch of Mountain Lion set for late summer, Apple has now started notifying developers that they need to start getting ready for the Developer ID program. An email sent to developers yesterday gives a brief rundown of the program and encourages them to get their IDs and start preparing their apps for the program’s launch.

A copy of the email was tweeted by @jonicious yesterday. Check it out below:

Do you think we’ll ever see an iOS-style “walled garden” on the Mac? Would that be a good move on Apple’s part? Tell us what you think in the comments.