There's a tool that does 3D presentations called Tao Presentations, just around the corner. See http://www.taodyne.com. It also does "real" 3D (i.e. stereoscopy or auto-stereoscopy on Philips or Alioscopy screens).

The description of slides looks close to what you are calling for:

slide "test",

    * "First point"

    * "Second point"

It doesn't output to Impress.js yet, but that sounds like an interesting opportunity.

I bet it would be fairly easy to plug this into org-mode. It already supports exporting to web-based presentation tools (I forget exactly which ones) so it's not without precedent. The tricky bit would be encoding the positions and transitions and effects, but that shouldn't be impossible.