An argument can be made, that is not an open environment, because (1) they use external cameras that have the whole room in their field of view, and (2) the room is totally white.
They (not ETH Zurich) can autonomously identify, track and chase targets in urban areas, without GPS. I'm almost sure juggling a ping-pong ball in a park would not be entirely out of the question.
I'm well aware of the robotic research and I chose my example carefully. The extra weight of a baseball, the grasping motion necessary, and issues of bounce and spin on an uneven surface makes it a more difficult problem than the pole balancing or the ping ping quadrocoptors.
They could not do the same out in a park.