from PCGamesHardware.de have managed to get their hands on the tech demo of Stalker: Clear Sky in DirectX 10.
According to the article the best way to see the DX10 effects is in smoke, rain and the so-called God rays. The article also includes a 4:31 minute long video that shows the game in action. As we can see from the video, the game has potential to force Crysis into oblivion.
You can check out the screenshots and the video here
. The article is in German but you can always use Google translation to get a general idea.