It seems Microsoft thinks it doesn't have enough money in the bank and now wants to charge developers of open source software $499 for the full version of Visual Studio.
To make sure developers don't use the free version of VS called Visual Studio Express to create desktop applications, Microsoft has removed the compiler infrastructure from the Windows 8 SDK.
This means that developers of open source apps will be either forced to create Metro applications only, or to purchase the full VS version if they want to create desktop applications.
Hardly in the spirit of promoting goodwill among budding developers is it.
Full story here: New obstacle for open source on Windows 8