Thanks for the link! I think their approach of including the real-world is very exciting and has just as much potential as completely virtual applications.

Edit: Just realized you were asking me a question. Well nothing quite as advanced. The user would look through their camera on the phone screen and draw directly on the screen and also be able to see other people's overlays, kinda like snapchat but in 3D and realtime. If I find the implementation I saw on HN I l link it.