The Book of Unwritten Tales is the most expected game in my List. I dont know if you know this german game already but take a look:
The game uses the Ogre3D Engine which is the most used opensource (lgpl) engine for commercial games i know. Some of the Developers talk about thier used techniques in the Ogre-Forum.
"The prerendered scene gets a paintover and is then cut into pieces (we call them "patches") that are drawn flat into the scene. Some are rendered in the background, some in the foreground and some appear at a "real" 3D position in the scene and so can affect the 3D characters and items. As many of those patches use alpha, special attention must be paid to the order of rendering and the z-buffer usage. By now, those things are controlled manually via xml-Files."
thats it for today.