According to Apple's press release, the store will be available in 90 countries at launch and will feature both free and paid applications divided into categories like Education, Games, Graphics, Design, Lifestyle, Productivity and Utilities.

In addition, the Mac App Store will offer sections highlighting "new and noteworthy" apps, "hot" apps, staff favorites and will offer search, customer ratings and reviews, again, very much like iTunes does now. It will also offer the same integrated checkout experience, where you can click once to download the app and then begin using it immediately, says Apple.

Unlike apps sold on the Web by individual developers, those who host their apps in the Mac App Store won't receive 100% of the revenue for apps they sell. Instead, the standard 70/30 split (developer/Apple) will apply. However, for many developers, that split is actually a bargain - not only will getting into the Mac App Store offer increased visibility, they will no longer have to worry with website hosting, bandwidth, billing and all the other sorts of issues that come with traditional DIY solutions... unless, of course, they plan to sell their apps both in the store and on the Web. (It will be interesting to watch how many developers actually shutter their websites entirely in favor of the store - if you're a developer, let us know what your plans are!)

Developers can learn more at ?http://developer.apple.com/programs/mac.

Meanwhile, Jay Freeman, creator of the Cydia App Store for jailbroken iOS devices, recently announced plans for a jailbreak Mac App Store. There are few details about the store, reportedly available within weeks, but it's likely to be a place where developers won't be required to follow Apple's list of restrictions (see examples here). Like Cydia for iPhone/iPod Touch/iPad, it will offer a chance for developers to have a place where unapproved apps can reside.