It's SO much more than that.

Here's a technical writeup that was on HN earlier this week - revolutionary stuff.

http://www.fxguide.com/featured/disneys-new-production-rende...

There are many ways of handling GI (which is basically, taking in consideration light that bounces though the scene in addition to that emitted directly by light sources). Until now, Disney used and hybrid approach rasterizing the main scene and raytracing some effects that a rasterizer can't handle. Now with this new renderer they have joined the full raytracing wagon.

In fact, they are far from being pioneers in the field (right now raytracing is widely used in production rendering), but it's a big step for Disney and they have built their raytracer from ground, allowing them to implement it with some clever tricks.