Here. From Jesse Ezell: Project Mono has decided that implementing WinForms natively on platforms is just too hard. They are instead going to implement a Win32 version and use WINE Lib for the linux / mac implementation. We'll see if they stay this way. IMO, if things don't change, WinForms on Project Mono has now become about as important as Microsoft 'Bob'.
Who wants to run on top of the WINE code? It has problems running normal Win32 apps, let alone .NET apps.