Sorry, let me correct myself.
AFAIK there is not Capacitive or Resistive touch screens larger then 22 inches. (edit: that are sold in volume)
Infrared, or camera, types can scale very large. HOWEVER, in order to work your display needs to be semi transparent in order to map objects close to it, as well. you need to think about the viewing angle of a camera.
In order to capture a 22 inch screen you need to be a foot back, a 36 inch screen 2 feet. 42, 3 feet. Not all of our walls can be turned into foot ball stadiums.