The Inquirer says we can soon expect a new DirectX upgrade which will incorporate some significant new features. The company said this at the Game Developer conference in London last week, and this also means that NVIDIA's and ATI's R600 next-generation cards will be ready to show their feature sets even bedore Windows Vista arrives.
It's a great decision as both Nvidia and ATI Shader Model 4.0 parts are expected sometimes toward the middle of 2006, before Longhorn arrives. We don't have any idea what it is going to be called but DirectX 9.something sounds like a reasonable guess.
If Microsoft decided to wait for the Longhorn for those new shaders, this would have meant that the next generation Nvidia and ATI chips would have had to wait for a few quarters before they would be able to get the full Shader Model 4.0 functionality.