In photoshop, a smart object is a photoshop file within a photoshop file. It would be great to have construction planes as smart objects. I want to model a small detail in a new alias file and place it with a construction plane in a differeent file. This would enable someone else updating this detail and I could just refresh the link. I also could move the constrution plane to move the position of the detail without loosing the construciton history. This would also keep file sizes down if the smart object is referenced instead of saved within the file.
Parametric modelling systems do this very well, it would make Alias feel less of dinosaur.