Yeah, Disney used a multi-plane camera to composite different layers together to create the illusion of depth. I haven't watched Sleeping Beauty in a while, so I can't specifically say if it was used in that film, but it had definitely been created by then, so I would imagine that it was.

A little bit off-topic, but what's the deal with this new Sleeping Beauty release anyway? I'm not planning on getting it because I got the 2-disc set that was released a few years ago. Is there any real difference besides another new restoration and the fact that it is officially part of the Platinum Collection line now (I always assumed the previous one was since it was a 2-disc set released during the Platinum Era with the same kinds of special features and documentaries that the Platinum Collection has overall)?