Futuremark has started talking about their next 3DMark publicly over at Beyond3D interview. The key feature and effect present in 3DMark2006 are Shader Model 3.0 support and HDR implementation that requires full SM3.0 support and FP16 textures & blending. Others cool implementations and changes include CSM (Cascaded Shadow Maps), soft shadows, heavier pixel processing load, increased arithmetic to texture ops ratio for the SM3.0 tests, at least 256MB of graphics memory to ensure no disk swapping, a new CPU test (most probably multi-core support).More details and screenshots over here.
3Dmark06 screenshots and details

VR-Zone and HKEPC got their hands on some information about the upcoming 3DMark06 benchmark.