It's been bugging the hell out of me, playing ArmA, and then flying through a flat cloud (with some occassionally ugly and random textures that don't fit, like a grayish purple over the rainy cloud) with a cheap skybox in the background. For it's time, it was wonderful. But now that the ArmA 2 can use this feature (volumetric clouds), will it? It's not exactly the most important feature, but it adds just that little extra bit of realism, seeing (and moving through) "fluffy" clouds.
Just throwin' this out there to the devs.
Either way, I can't see ArmA 2 being anything less than an improvement over ArmA.
-Pedgi