NOTE this tutorial uses Adobe - After Effects CS3 and Maya v8.5 and Higher. Render Layers & Material Overrides 101 : Part 1 - Outline:

What is a Render Layer
Create a Render Layer
Add, Remove & Select objects in a Render Layer
Preset Overview and Usage
Layer Material Overrides
Create Scene-Dependant reusable ID pass Material Overrides
Help overview


Part 2 - Render Layers in production:

Compositing and Post benefits of render passes allowing control over each element in a 3d scene.

This tutorial also uses Adobe - After Effects CS3