I think you guys misunderstand the intended purpose of 3 and 6 displays. It is not to create a large flat surface. Right now they are working within the limitations of the shaders. The real purpose is to create a 360 box of vision, and that amount of displays is perfect for such a goal.
However, in order to do it you need to purpose build your shader and displays for such a setup. For instance if the military expanded their simulation technology, they would probably pick an HD5870 Eyefinity 6. In the shader they would create 6 cameras (Up, Down, Front, Left, Right, and Back) Then have them displayed in the appropriate directions in real life for a full 360 degree viewing area. This can also be done at the consumer level if the developer extends such features onto the user. However such a setup does not make sense for a consumer. 3 Displays for a 180 degree vision range makes more sense.
However, in order to do it you need to purpose build your shader and displays for such a setup. For instance if the military expanded their simulation technology, they would probably pick an HD5870 Eyefinity 6. In the shader they would create 6 cameras (Up, Down, Front, Left, Right, and Back) Then have them displayed in the appropriate directions in real life for a full 360 degree viewing area. This can also be done at the consumer level if the developer extends such features onto the user. However such a setup does not make sense for a consumer. 3 Displays for a 180 degree vision range makes more sense.