Microsoft is really trying to get app developers to embrace their Metro interface to the point they’re pulling the free development tools for Windows 8 desktop apps. Windows 8 is intended to be an identical experience whether on a desktop or mobile device and Metro is the development model that does both. Desktop-only apps can still be created but it’s going to cost you $500 for Visual Studio 11 Professional (free for students).
Like Gruber, I find Microsoft’s all-in approach to this interesting if for no other reason than it’s so different from Apple’s keeping iOS and OS X as separate experiences. Of course, Microsoft has the cash to make something like this not be fatal should it fail, which tends to make this less than a “bet the company” proposition.