Interview started with a simple phone screen by one of the managers, and then after a week or so, I was call in to do a face to face. The face to face interview was with a small panel of engineers. It was a little intimidating at first, but after a while I got the sense that they were really trying to understand who I was, and what kind of life experiences I'd had.
I was quizzed about pretty much everything on my resume, and was asked to go in depth in a couple sections and explain what my involvement was (assuming it was a group project). All in all, it was a good experience and not too stressful.