The Chinese language website Hardspell has got its hands of some screen shots and a short video of a DX10 demo from ATI. It is called Light of the Earth as far as we can tell, or possibly Global Illumination. It shows of some of the DX10 light and shadow effects quite well, but the graphics don't look too impressive, at least not for next generation hardware.
The video shows the light source moving around and the card used - we're guessing it's a Radeon HD 2900XT - only manages to produce around 45 fps, so it seems to be quite taxing on the hardware. The demo is Vista only, but this is hardly unexpected as DX10 is only available for Vista. You can find more screen shots and the video here