OS X's Gatekeeper is a great feature that makes sure the code you're about to run on your Mac is really the code you think you're about to run. We've all seen the pop up reminding us that an application isn't signed and built by developers trusted by Apple, and we should be sure we trust the source we acquired it from before we open it. It's a vital first-step towards security management, and that means it's one of the things that will always be given the highest scrutiny and updated by the folks in Cupertino.
Apple sent out a PSA for developers today that reminds them about code signing for the upcoming Mavericks 10.9.5 release. For an application to remain trusted, developers will have to make sure the code is signed using OS X Mavericks 10.9 or later and create a v2 signature. This will also carry over into OS X 10.10 Yosemite. Apple says applications signed using these new methods will also still work for older versions of OS X, so for users everything should remain seamless.
For more information and details, see "Changes in OS X 10.9.5 and Yosemite Developer Preview 5" at the Apple Developer site (opens in new tab).
