Or create that effect in Photoshop, where you have much more control of it...in the case of the image obove that would work as well..even better than a fog-effect in Maya....and the rendertimes would be much faster...that's the way I'd do them (take a look at my turntable, and you can see a similar effect...you can find them in the WIP section)

cheers

b u l l e t