This is dependent on how much server lag you are experiencing. If you die in an instancewhile the server is experiencing a bunch of lag you will sometimes ghost above your corpse for a brief period of time before you are transported back to the spirit healer/GY. If you can run quickly enough, before the server catches up and moves you to the GY, you can pass through an instance portal and it will zone you to outside the instance as a ghost. Then all you have to do is pass back through the instance portal and you rez w/o the need for a run from the GY.
I have repeated this process numerous times over the last few days. Obviously, this is of limited usefulness and depends greatly on how much lag the server is experiencing. It's best if you die close to the instance portal. It's a nice little time saver though when you can manage it.