Valen Wagner shares his Script for color correcting color swatches in Maya when working in a linear workflow. Gamma Correct Color Swatches will allow you to simplify the process of creating Gamma correct swatches simply by selecting the material shader and running the script, a window will appear asking you to select which shader attributes you want to apply the gamma correction to, and what the gamma correction will be, and what color you want as well.
This script is for someone working in a linear workflow that requires a gamma color correction on all shader color swatches (you know who you are!)
The Gamma Correct Color Swatches script currently supports Maya materials and a few Mental ray materials as well. For Maya materials it supports anisotropic, blinn, hairTubeShader, lambert, oceanShader, phong, phongE, shadingMap, surfaceShader, useBackground, and envFog. For Mental Ray it currently supports dgs_material, dielectric_material, mi_car_paint_phen / mi_car_paint_phen_x / mi_car_paint_phen_x_passes, mi_metallic_paint / mi_metallic_paint_x / mi_metallic_paint_x_passes and mia_material / mia_material_x / mia_material_x_passes.