Preview at WWDC likely in June, followed by September launch.
Mac App Store Hits 10,000 Available Apps
Our own sister site AppShopper confirms the milestone, currently indexing 10,339 applications in the store. Apple launched the Mac App Store in January 2011 and has quickly moved to offer its own major software titles through the marketplace, viewing it as the future of software distribution on the Mac platform. Even OS X Lion itself is distributed via the Mac App Store.
The 10,000 Mac App Store apps pale in comparison to the 600,000 apps available through the iOS App Store, but the Mac App Store remains a success by desktop software sales standards. Last December, the store passed 100 million downloads, making it the "largest and fastest growing PC software store in the world".