I found this today its somewhat useless, maybe you can trick your friends or hide from the enemy.
1.Go into the empty halaa building that has moose head/podium in it.
2.Jump onto the podium edge, its will take several tries to get the right spot.
You will know your in the right spot when you angle your camera and disappear.
Heres some screens.
Stand /jump here on podium
The fat tauren is invisible even though he right next to me.
He still there but completely invisible and cannot target him.