After releasing the Golden Master version of OS X Mountain Lion, Apple has started accepting Mountain Lion apps into the Mac App Store.
An email that Apple sent to registered developers, Apple said:
Make sure your apps take advantage of the great new features in OS X Mountain Lion when the world’s most advanced operating system ships to millions of customers worldwide. Download OS X Mountain Lion GM seed and Xcode 4.4 GM seed, now available on the Mac Dev Center. Build your apps with these latest seeds, then test and submit for review.
You can also submit iOS apps that take advantage of the new cross-platform Game Center Groups, so they’ll be available when OS X Mountain Lion ships.
At the moment, OS X Mountain Lion is available only to registered developers. The final version will be available to customers through the Mac App Store later this month. Apple will sell the new release at $19.99.
Source: Mac Rumors