Jay Freeman, widely known as Saurik, announced that a Cydia-like App Store that will offer open source Apps for Mac OS X is under development.

Freeman is the brain behind Cydia App Store on jailbroken iOS devices and he talked about jailbroken Mac Apps Store at 360 MacDev, reported TUAW.
The Mac OS X version of Cydia store would be available within weeks, obviously after the Mac App Store shows up. There's no specific name being used but Freeman is being quoted referring the app store for Mac OS X as Mac Cydia.
At 360 MacDev, Freeman explained that his version of Mac Cydia Apps Store would act as an extensions provider to unleash the power of Mac OS X. Cydia never promoted cracked or pirate apps but acted as an extension to download open source apps and make the best of jailbroken iOS devices.
Today, the Cydia App Store offers about 30,000 different apps (both paid and free) for jailbroken iOS devices.
Mac App Store won't support in-app purchases and it would be more like a web store with loads of free as well as paid apps. Freeman further criticized Apple's restrictions and bad documentation for developers. Looks like Apple will have to go through a series of changes in its documentation for Mac OS X desktop developers in order to make its Mac App Store live and kicking.
Rival Google is already working on Chrome Web Store but it is more of a Chrome browser based store for Web Apps and would also work on Chrome OS based netbooks. Compared to that, Mac App Store would be more Mac system specific.
(Source: Techtree)