Apple has released a notice to registered Mac developers informing them that the deadline to implement sandboxing in Mac App Store apps has been extended to June 1st. The deadline had initially been set for November, and was later postponed to March 1st.
We have extended the deadline for sandboxing your apps on the Mac App Store from March 1st to June 1st to provide you with enough time to take advantage of new sandboxing entitlements available in OS X 10.7.3 and new APIs in Xcode 4.3. Get more details about sandboxing your app and find answers to FAQs.
Sandboxing is a way to restrict an app’s access to only those system resources necessary for the app to function. This reduces the chance for any app to behave improperly and potentially compromise your system or the security of your data.
Starting June 1st, all new Mac App Store apps submitted to Apple must be sandboxed, and apps that already exist will not be able to submit additional updates for their apps until they implement Apple’s sandboxing.
While Sandboxing can be a very good thing for users, helping to keep their Macs stable and secure, apps that are deeply integrated into OS X, or that require access to certain system-level functions (like modifying the boot drive) may not be able to exist in the Mac App Store.