Microsoft just made its DirectX SDK August 2007 version available. Besides the usual small corrections, there are two major innovations.
The first is a preview of DirectX 10.1 technology which will be found in future GPUs. DirectX 10.1 accompanied by Shader Model 4.1 is a minor evolution of DirectX 10 mainly involving more flexibility in the use of certain type formats of data and the possibility for developers to choose the position of samples used in antialiasing. Note that SP1 for Windows Vista is necessary to have a glimpse of this preversion of DirectX 10.1
The second innovation is called XAudio2 beta1, the much awaited successor of DirectSound for games. XAudio is the API used to manage sound of the Xbox 360. The version 2 is now Windows (XP and Vista) compatible, which now facilitates the development of video games on Windows and Xbox platforms. XAudio2 is of course capable of managing multi-channel audio systems with all the modern effects and was conceived to take advantage of multicore processors.
Finally, note that Microsoft announces the definitive abandonment of DirectX 8 and previous versions starting with November’s SDK. The SDK, as well as some additional details on its innovations is available here