I see it working with the PS4. With the PS4 ON just press "Action Menu" in the remote, and there should be the option for the PiP. It doesn't work with Android apps, though (meaning you can't put an app into a window and start another app), unless it is specifically implemented in a app itself. VLC Beta has an option in the video player that puts it in a window. After that you can manage it holding the Home button.
Still, there isn't much one can do with it. At least the few times that I tried it, if you have something in a windows and start a video in foreground (or anything that uses the GPU, I suppose), the window disappears. But give it a try yourself, it's cool for a couple of minutes.
