Cyber Dimensions....

The good news:

DirectX 11 will be available on both Vista and Windows7. It is good to hear DirectX 11 will not be limited to Windows 7.

The better news:

DirectX 11 will have better compatibility with DirectX 10 hardware than most expected. What does that mean? Yes, there is some confusion over the "11 running on 10 hw" part of the announcement.

There are parts of the new API that are hardware independent, those can indeed run downlevel. The mult-threaded resource handling, for instance, can be enabled to run on DirectX 10 class hardware if the IHVs ( ATI, Intel, nVidia ) update their DirectX 10 drivers. Think of that part of it as "11 on 10".

Then there are parts of the new API that do require new hardware support and will only run on DX11 class hardware. The hardware tesselator and Shader Model 5.0 are examples of those parts.

The best news:

This makes it clear that Microsoft has not "forgotten" PC gaming; which some critics seem to think. Which is a very good thing.

The "stuff not told yet" news:

There are a couple of things for developers not disclosed in these releases, and when the DirectX 11 SDK comes out I think developers will be pleasantly surprised.

Just as Windows 7 will have Windows Vista at its foundation, and will simply be built on top of it, being an evolutionary release, so will DirectX 11 be based on DirectX 10.