Sources have told Mary Jo Foley at ZDNet that the Courier dual-screen tablet will run Windows 7, Microsoft's latest operating system. However, standard Windows 7 applications will not run on Courier.

Applications will be specifically tailored to take advantage of the touch-screen capabilities and unique display configuration of Courier. This way Microsoft can insure that the user experience on Courier is optimized for the hardware.

More details of Microsoft's Courier tablet have been leaked to gadget blog Gizmodo. Like previous videos and photos this concept animation was produced by Pioneer Studios, a division of Microsoft Entertainment and Devices.

Microsoft is said to be at a late prototype stage in product development where they've begun to show Courier concepts to outside agencies. This video shows an in-depth depiction of how one might use the dual-screen device to work on a collaborative project. The highlight of the video is Pagestream, the heart of the user interface.

File this under the many items in the "we don't know yet" category. Common sense dictates, given the overwhelming success of the iPhone AppStore, that Microsoft would model software and applications on the Courier in a very similar fashion.

After all, Microsoft already has its own Windows Marketplace for Mobile with several hundred apps available for the Windows Mobile operating system.

That said, we certainly don't presume to know what actually happens inside the Microsoft brain trust. So, check back for more info, you'll know when we know.