Never tried it but if the blender node can be given a unique tag (eg name) it should be possible to write a python script to scan through a scene and copy a value to each node with the same tag it finds.

In an ideal world how would you see this being used? For example would the user set the colour on the currently selected prop's mat room and the script take the value from there, or do you see it as clicking on the side menu to bring up a colour picker? Also would this be applied to all your props or just the currently selected one?