I basically got this interview through my university and the position was for the PUP program. The interviewer asked me fairly simple questions like why do you want to work for Pixar; if you could make any movie in the world, what would it be about; why are you interested in animation; asked about previous experience with 3D animation software/pipeline; discussed previous projects involving graphics and computer science; and showed him my website.
I was later asked for my demo reel in an email, but was not accepted afterwards.