This was reported a while back as an added function. I remember testing it about 2 months after it was initially reported but it wasn't working. I asked an Nvidia employee about it ~1 month ago and they said it was "a half finished feature that got put in early." At that time, it was not working.

As of yesterday, it seems to be working for me. Anyone else? Its particularly useful in apps like Sling that do not have on screen pause/play buttons. You do have to double tap fairly quickly for the command to register.