As many of you know at //build we announced that there will be a new .NET target framework for Metro style apps. To learn more about the goals of this new target framework I encourage you to watch Krzystzof Cwalina’s build talk "A .NET developer's view of Windows 8 app development".
One of the things we know people want to do is reuse existing .NET code but due to the constraints on Metro style apps it is not possible to directly reuse existing .NET class libraries nor is it always possible to simply recompile existing code. We realize this is going to be a pain point for many current .NET developers so we are working on a guide at the .NET for Metro style apps overview page which will assist developers in translating their existing .NET skill set into the Metro style apps world. Sometimes that means explaining why something was removed and other times it means giving another .NET or WinRT API to call instead. Today the page is limited but we are actively working on it internally to update it with more data for Beta and RTM.
For a demo of the kind of things you are likely to run into while porting code I suggest watching Daniel Plaisted’s build talk "Bringing existing managed code into Metro style apps".
While we are looking at many forms of feedback we would greatly appreciate any feedback on issues you run into while porting existing .NET code to Metro style apps. Please leave feedback in the comments or on the forums.