I'm looking for software that can use a projector to "illuminate a whiteboard" with white light. Then let local or remote computer users "draw" on the whiteboard by masking the projected white with black or color. Local users could still use dry-erase markers too, and It needs to be able to take snapshots of the board, compositing the real world markings and digital markings (Though a still of the remote video would work).

Has anything like this been polished at least to the 50% stable mark?

What projects should I look at?

That laser-grafitti program is similar to what I want, except I'm fine with the only digital input being a mouse cursor. The only need I have for the camera, is so that local dry-erase markings can be shared/captured.

I'm also looking for suggestions for GNU video-switching software. Attach 4-6 usb cameras, and mics. Then mix all audio, and tile all video, until one mike is X percent louder than the rest, which would cause its corresponding camera to go fullscreen.