DirectX 10:
- Fixed pipelines are being done away with in favor of fully programmable pipelines (often referred to as unified pipeline architecture), which can be programmed to emulate the same.
- New state object to enable (mostly) the CPU to change states efficiently.
- Shader model 4.0, enhances the programmability of the graphics pipeline. It adds instructions for integer and bitwise calculations.
- Geometry shaders, which work on adjacent triangles which form a mesh.
- Texture arrays enable swapping of textures in GPU without CPU intervention.
- Predicated Rendering allows drawing calls to be ignored based on some other conditions. This enables rapid occlusion culling, which prevents objects from being rendered if it is not visible or too far to be visible.
- Instancing 2.0 support, allowing multiple instances of similar meshes, such as armies, or grass or trees, to be rendered in a single draw call, reducing the processing time needed for multiple similar objects to that of a single one.
DirectX 10.1:
- Mandatory 32-bit floating point filtering.
- Mandatory support for 4x anti-aliasing
- Shader model 4.1
DirectX 11:
- Tessellation to increase at runtime the number of visible polygons from a low detail polygonal model.
- Multithreaded rendering to render to the same Direct3D device object from different threads for multi core CPUs.
- Compute shaders which exposes the shader pipeline for non-graphical tasks such as stream processing and physics acceleration, similar in spirit to what OpenCL, NVIDIA CUDA, ATI Stream achieves, and HLSL Shader Model 5 among others.
- Two new texture compression algorithms for more efficient packing of high quality and HDR/alpha textures and an increased texture cache.
All this info was on Wiki.
