Microsoft is giving a sneak preview of its upcoming Windows Store, which will be part of Windows 8. Developers will be able to earn up to 80% revenue share on apps sold through the platform. It starts at 70% for new apps, and jumps to 80% once the app makes $25,000. The individual registration fee is $49 ($99 for companies).

The store will be available when Windows 8 Beta is released.

The company has laid out four basic principles that it wants the store to operate by, and for developers to be informed by: designed for discovery, flexible business models, transparent terms and best economics.

“Combining the broad reach of Windows, a new developer platform, best-in-class developer tools, a reimagined user experience, support for new chipsets, and a built-in Store with industry-leading business terms—Windows 8 is the largest developer opportunity, ever,” says Antoine Leblond, VP of Windows Web Services.

“We designed the landing page to push compelling apps to the surface,” says Microsoft’s Ted Dworkin. “We use categories to help organize the apps—the latest, most popular, and fast rising apps all have dedicated lists surfaced here. You’ll see personalized app recommendations and also topic pages that promote apps related to editorial themes, helping surface what would otherwise be hidden gems.”

The store’s catalog will be indexed by search engines, and the search results will point to web versions of app listings. These will be published based on the same content provided for the actual store listings.

Developers can promote apps from their sites with “available in the Windows Store” logos, as well as built-in promotion in IE10. Developers can add a line of markup to promote the with the app button within the browser that will be visible to anyone using IE10 on Windows 8.

The store will be available in 231 markets worldwide. “We’ll have a number of market-specific catalogs, tailored for those customers, and a ‘rest of world’ (ROW) catalog for all other markets,” says Dworkin. “Developers can choose the catalogs in which their app is listed, and we will continue to increase the number of market-specific catalogs and payment providers over time as we evolve the Store service.”

Developers can offer customers trials and in-app purchases through the platform. They can also keep third-party authentication and transaction systems in tact. They can also use whatever ad platform they prefer.

“We want to increase predictability and eliminate any capriciousness in app certification,” says Dworkin. “We do this by providing every developer with the technical certification assessments—the App Certification Kit —as part of the SDK. We also provide app acceptance guidance, in plain language, in our app certification policies.”

You can view those policies here.

It’s worth noting that there are over 1.25 billion Windows users on the planet, according to Microsoft. The company has sold over 500 million licenses for Windows 7. Those can all be upgraded to Windows 8 on the day it ships.

Microsoft is kicking things off with a “First Apps contest”. This gives developers a chance to have their apps featured in the Windows Store for Beta. More on that here.