this is kinda cheap, but the majority of the people rendering to clay like this are actually just using a preset maya 7 has. all ya gotta do is select all your objects and add them to a new render layer. after that, right click on said render layer, go to presets, and choose occlusion. that should give you the style of render that you see these guys pumping out like it's nothing...
in my opinion, though, rendering with these settings or with final gather and global illumination etc. leads to people not knowing how to actually create a good light setup. you get people that don't understand the concepts of light linking, and people that don't realize that the occlusion render usually looks too blown out on top to actually look good or get good comments and criticisms from.
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