Today during its MIX developer conference, Microsoft shared more details about Windows Phone 7 and the tools developers can use to write applications for it. In a shocking revelation, Microsoft admitted to a decidedly Apple-like approach to how it will distribute Windows Phone 7 apps. All apps must be approved by Microsoft, and can only be distributed via the Windows Marketplace for Mobile.Well, this is interesting. The MIX conference keynote offered up all sorts of details on how developers can use SIlverlight and XNA to write applications for Windows Phone 7. The SDKs went live earlier this afternoon, and are free for anyone to download and test out. Microsoft also introduced a new version of the Marketplace for Windows Mobile.

The new version is called Windows Phone Marketplace. Microsoft's Todd Higgs, in an interview with Engadget, said that the one-and-only place for Windows Phone 7 users to get applications for their devices will be through the Windows Phone Marketplace. Apps must conform to Microsoft's standards and won't be available until they are certified by Microsoft.

Let's see, where have we heard this story before. Oh, right, Apple, the iPhone, and the iPhone Apps Store. Since its launch, the only "official" way to get applications for the iPhone has been through Apple's iPhone Apps Store. iPhone apps must be approved by Apple before they become available to end users. The only way to get unapproved apps is to jailbreak the iPhone (which voids the warranty) and download apps through Cydia. (This begs the question, will WinPho7 devices get the same unsanctioned treatment from hackers?)

Higg's said that the company will do everything it can to avoid the problems experienced by Apple. Apple has famously dragged its feet on app approvals, providing developers with little or no feedback about their apps. Microsoft said its app approval process will be more transparent and predictable. I'll believe that when I see it.

Other details were exposed by Engadget.

Marketplace membership for developers will cost $99 a year. That includes five apps. Microsoft hinted that it may increase the number of apps that can be submitted under the yearly $99 fee.

Developers can update their applications for free, and users won't be charged to update them, either.

Developers will be able to offer free, ad-supported apps, though the apps will still have to pass Microsoft's scrutiny. Final guidelines for how this works haven't been firmed up.

End users will be able to browse and buy apps and games through the Zune desktop client on your PC.

Windows Phone 7's story is just beginning to emerge. After today, there are much better selling points to convince developers to get on board. Microsoft is still a long way from success, however.