V 3.0: Lens flares & dirt, visor reflections / water droplets, god rays, depth of field, night & thermal vision scopes, dynamic wet surfaces with reflections, rainbows, volumetric light & fog, colored speculars and many other effects.
Just another couple of in-game screenshots.
Subtle, if only there were two rainbows.
Actually there are two rainbows - the second one is just much less prominent, so you won't see it when the overall intensity is low as it is in this picture ;)