Mac App Store
To install it, simply upgrade your Snow Leopard to version 10.6.6, which already includes the Mac App Store.
If you have your Apple phone or one of the other iOS-enabled devices and you’ve used the App Store, you already know how to use the Mac version of the App Store. The App Store not only makes it easier to locate and purchase applications through categories, highlights, and lists of popular applications, it also brings the simple mechanism of installing and updating iOS applications to Mac OS X.
Needless to say, we can and will continue to download and install applications externally to the store as before, but the Mac App Store is a win-win for both users and developers. A new place to centralize and simplify the management of Mac applications, forgetting about serial numbers, installing on multiple computers with a single license and forgetting, if you will, about our so far beloved dmg files.
Look out for Apple ! Much more information about the Mac App Store will follow shortly. Now, enjoy!