Don't get too excited, I'm just thinking about it.
The graveyard orbit is located above the Geostationary ring, where most of our telecommunications satellites operate. Many of them are left with sufficient fuel at the end of their mission life to boost them into this orbit, where they are out of the way and not contributing to the debris problems in GEO.
It's not that they are now simply inert - I have seen discussions of how material in the graveyard orbit can impact on spacecraft in GEO - and let's not forget that we're talking about many-body problems here with all the instabilities of non-linear systems, so they may not always just circle up there serenely - but to all intents and purposes nothin' is going on in the graveyard orbit. It's not premium space, no-one wants it at the moment for anything except as a junkyard.
So if we were going to propose anything for world heritage listing in space, this may be a good choice: uncontroversial in terms of competition for space resources, without the nationalist interests of places like the Moon, and easy to enforce!
The WHL cannot be applied to space at the present time, but I'm working on this with the help of my graduate student Nigel and space lawyer Anthony Wicht.
The question of its significance is another I'll have to investigate.