Evolution, not revolution
In a blog post earlier this week, Microsoft's Chris Flores said that Windows 7 will be an evolution of the Vista kernel and "one of our design goals for Windows 7 is that it will run on the recommended hardware we specified for Windows Vista and that the applications and devices that work with Windows Vista will be compatible with Windows 7."
That's good news, of course, but you'll have to wait for more details. Flores said that releasing information too early causes confusion. "We know that when we talk about our plans for the next release of Windows, people take action. As a result, we can significantly impact our partners and our customers if we broadly share information that later changes." The rise, fall, and final disappearance of the new file system in Vista is probably part of what he had in mind.
On the other hand, if Microsoft doesn't do better, early work with its partners regarding drivers and compatibility, the company -- and its customers -- will be right back in the (Vista) soup.
(Disclosure: I own a small number of Microsoft shares.)