One of the questions we asked NVIDIA was what performance differences and other graphical enhancements we will see between DirectX 9 and DirectX 10. NVIDIA has kindly provided inCrysis with some comparison screenshots to show you clearly some of the enhancements you'll see with DirectX 10.

UPDATE: Added 4 "Detail Levels Compared" screens, provided by Crytek.

Same images as plain links:

3D Waves (DX9) 3D Waves (DX10)
Motion Blur (DX9) Motion Blur (DX10)
Mountains (DX9) Mountains (DX10)
Sun Shafts (DX9) Sun Shafts (DX10)

Detail levels compared

Low (DX9)
Medium (DX9)
High (DX9)
Very High (DX10)