[berkut]

Pixar's generally ahead in terms of story, animation (they hand-animate everything) and look (shading and lighting), but in terms of pure tech, other companies like Weta, ILM and SPI are generally ahead of them as they work on multiple shows at once and per year.

SPI have been using full GI pathtracing with Arnold renderer for the last 5 years, and Blue Sky (studio which did Ice Age) has their own GI raytracer they use as well.

Also, Pixar don't actually have that big a renderfarm - they don't need it. Other places like Weta and ILM have renderfarms that are much bigger, but are used for multiple productions at once, and for doing things like compositing and fluid/cloth/physics sims.