The Bear Who Loved Vodka:
Backgrounds are made from 2D planes in 3D space with alpha layers and hand painted texture on them.
The characters are made in 3D with some kind of edge detection for the outline and a ramp shader the shading/ highlights.
Some elements whitch move in the background are made in 3d with eather the same edge detection shader or simple drawn on black lines at the edges.
The slight use of paint texture makes this animation look like the pixar concept images.
^not the best example but will do^