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.