updated 05:19 pm EDT, Tue October 22, 2013
Should allow older Macs to remain useful
Apple is bringing a "previous versions" feature to the Mac App Store, according to an official memo. Developers are being informed that unless they specify otherwise through iTunes Connect, Apple will now be allowing Mac App Store shoppers to download the latest version of an app that remains compatible with their version of OS X. The Mac App Store is accessible through Snow Leopard, Lion, Mountain Lion, and Mavericks.
The feature mirrors one introduced in September for the iOS App Store. In both cases, the technology makes older Apple hardware more viable, since users have access to all of their essential apps, regardless of whether or not they're locally installed or backed up.