Does anyone (here) know if Windows 8 will have a sort of fat exe that one can compile with Visual Studio 2012 that will be supported on both ARM and x86 machines? I am guessing not, since you can't create fat binaries that will execute 32 or 64 bit code so far as I am aware (only solution available that I am aware of is 32 bit that creates a 64 bit executable on the fly).
It seems like it would be helpful of Microsoft to extend exe or create a fat binary format for Windows 8 and beyond at least that would allow one to compile a single executable for Window's expanding palette of platforms.
edit: The following link shows how to compile an ARM exe in the first dev preview. Figured I would add that because it gives no hint of fat binary support, but it is also early in the game. I don't think not having it now rules it out as a possibility. Compile for ARM
The need for fat binary support in Windows 8 is mitigated by the requirement that binaries for the ARM platform be distributed through the Windows app store. Modern apps are compiled to a single package.