Is this only applied on an individual basis? After having played around in .990 for some time, I noticed some quirks that I suspect can be attributed to imperfect handling of gamma. For instance, constellation lines with MSAA turned on become a tad bit darker, and some visible "blobs" in the lines emerge. Also, distant and faint stars, without the star desaturation slider turned up to compensate, also seem to gradually saturate as they get dimmer, consistent with the effects of gamma-space rendering. By turning up the in-game gamma slider to 2, some of these quirks appeared to vanish (at the price of ending up with washed out visuals), further corroborating my suspicion.
Gamma correction for planet textures: parameter in catalog scripts and slider in the editor