Less of a life saver now that you can walk with full inventory, but still a really cool mechanic.
You can slingshot launch your character by canceling a grapple right before you hit the wall.
On controller, grapple at something from a slight angle, and press B right before impact to cancel the grapple. At the same time, swing your camera in the direction you want to launch. Your characters hip should slap off the wall and launch you in your camera direction.
On PC, only difference is you use the mouse scroll wheel to change weapons instead of pressing B on the controller.