Here's a few screenshots taken in roughly the same place showing the comparison of the DirectX 9 and DirectX 10 version of the game. This is perhaps one of the hardest things to show in screenshots alone, which is why I'm looking into capturing a video of the performance to show the true performance. 

I think we'll all agree there's not a lot in the screenshots, so HD2900XT owners aren't missing out on much at the moment. The single most noticeable difference going from DX9 to DX10 is the smoke. Smoke in DX10 is beautiful, acts like it should, get blown around and just hangs in the atmospherefor that perfect eerie mist.