That library doesn't look to be using 3d. Just rotation and some shading.
Anyways, I had the idea to do a cloth simulation to do the page turning. Works pretty well when it's stiff enough, maybe with some slight jiggling. But it does let you drag the page like a sheet of paper.
dropbox.com/s/hrzwjyr7y0erwt7/verlet_page_turn.c3p
I didn't come up with a nice way to do two sided pages like dop's examples. Maybe it could be doable by offsetting a second page by the vertex normals.
Multiple pages would need more work. I thought someone else made a working page turn example before, but all I could find were old dead links. Oh well.