My toon died, and I decided to have the ghost run around Azeroth to see where a ghost can go. The ghost ended up in a completely different zone far away from where the toon had died. In that zone I found a spirit healer where it appeared to be possible to graveyard rez, although I didn't actually do it. So in theory it's possible to travel by having your toon die and then corpse-run to a different zone.
Before I ever use that method to travel, I need to know whether it would be considered an exploit, because I'd rather not get banned. Please let me know.