With online app store fast becoming an integral part of the value proposition of the smartphone platform, Microsoft said in a recent announcement that it is introducing a new set of policies to be used for the Windows Phone 7 Marketplace.

Similar to the Apple App Store, developers seeking the membership for the Marketplace – which has been running for the last eight months, offering wide-ranging software for Windows Mobile 6. x – will have to pay an annual charge of $99.

The Marketplace membership will allow developers to submit five free applications as well as an unlimited number of paid applications – on a 70-30 revenue sharing basis. Free apps in access of five will entail a submission cost $19.99 each.

Furthermore, the business model that the Marketplace apps will be able to use will include: free, paid, ad-funded, and ‘freemium’ – in which basic functionality is free, but premium features involve an unlocking fee. However, marking a deviation from the App Store, the Marketplace will include a new mechanism that will allow trial modes for a limited time.

Meanwhile, in an attempt to keep controversies at bay, Microsoft has also clarified that no porn or sexually suggestive content will be allowed at the Windows Phone 7 Marketplace. In fact, all apps that are submitted will need to meet certain app certification requirements.