“Zeth Willie” throws up some quick notes in the form of a great general overview of creating a linear workflow in Maya for Mental Ray rendering. Be sure to check out the Maya Mental Ray Linear Workflow Overview tutorial at WillieWork here.
Zeth Willie has also updated the zbw_gamma script that works by shader selection and sticks gammas into the color channels. You can also adjust any/all gamma nodes in the scene or delete them globally.
A quick little jaunt through of the basics (some good, some pitfalls) of using color management stuff in Maya 2011