Here we look at building a multitouch setup using an infrared light source to light up fingers/objects placed on the surface and a camera to track the blobs....
How To Build a Multitouch Table - Part 1
Multi-touch interface (from Adobe TED)
MultiTouch Table mono 70"
Dell S2240T multi-touch monitor
Multitouch wall Cleveland Museum
MultiTouch Input - Unity Official Tutorials
Low-Cost Multi-touch Whiteboard using the Wiimote