Check out this new "Warhammer: Age of Reckoning" cinematic the insanely talanted guys at Blur Studios did:
It's done in mental ray (except some certain passes like particle work done in 3ds Max Scanline renderer (& maybe other renderers as well*)), and I even had the opportunity to render some of these characters myself, which was fun.
It's a suitably epic piece of work, I'd say.
What may interest people is that this is largely lit by physical sun&sky, and is using final gathering for indirect light. Clearly, the era of "fake everything" and "you can't use GI in production" is coming to a much needed close.
* = A ton of Particle work was done in FumeFX, which isn't available for mental ray quite yet. But a little bird has told me that this isn't too far into the future....