TWiT.tv will be coming out for Windows 8 and Windows RT!
I'm currently in the early stages of creating TWiT.tv for the new Start Experience / Modern UI / Metro. I am beginning this endeavor as a somewhat academic exercise in seeing what it takes to migrate a Windows Phone 7.x app to Windows using the new WinRT APIs, and perhaps that might even include an update for Windows Phone 8. I'd also like to go beyond the functionality offered in the phone version. The use cases for a phone versus a tablet or a PC are significantly different and the two applications will reflect that.
In my experience thus far the WinRT API is more capable and reliable than the Windows Phone API. I am very disappointed with the Windows Phone 7 environment, it lacks stability, robustness, and performance is often questionable. In hindsight I should have seen that disappointment coming because of the combination of a Windows CE kernel with a smattering of Silverlight on top was always doomed for such a fate.
At any rate look forward to more updates and with any luck TWiT.tv for Windows under the Christmas tree.