Awesome application! I like it. After playing around with it for about 15 minutes I got a browser error. The image below is that error:
I take it that when the user is in 3d perspective, he/she can't place objects on the floor? If so, I think from a design perspective the interface should indicate that. Perhaps have the items in a subdued state when its in a 3d perspective.
How many developers are on this project and how long have they been working on it?