The Microsoft Tablet: Code named "Codex"
This is just speculation so take it with a grain of salt.
If Microsoft produces its own, branded tablet it will run a slightly modified version of Metro, but would be built on top of Windows RT (ARM). It will be either be a 10in. or 8in tablet, with rear and front facing cameras. It will have both pen and keyboard dock accessories. The screen will be at Retina quality but the big news will be it will make use of the Microsoft's Surfaces Pixel Sense technology. The Pen was built in conjunction with Microsoft Research and come included; the dock and keyboard sold separately. The Codex will be aimed at the e-reading and education market, but will be compatible with all Windows RT apps. It will come with a series of applications built from the Courier project, so Live Journal along with new productivity apps. The cheapest model will run about $200 with tax.
Basically the tablet will be a showcase for Microsoft Applied Hardware Group and Microsoft research; it will have a dedicated (possibly separate) store for books built with Barnes and Noble. It will be designed and promoted as not to directly compete with PC partners; but will most likely be built by either Samsung or Nokia. The UI will be modified to fit its role as educational/reader