Happened upon this. Reminds me of a macbook pro keyboard replacement a while back, one screw stripped, and of course there are (around) 67 screws that hold in that keyboard. One in 67, yeah, it happens to everyone from time to time. <cringe>
For completely rounded out, stripped, small screws in iPhones, iPads, iPods it is possible to firmly press the blade of an xacto into the screw at around a 2 degree angle. With enough pressure the exacto will cut into the side of the screw hole and the point will grasp the opposite inside which should give you just enough leverage to slowly back the screw out. If you use this method, use patience as you start to feel the blade "grip" the screw. And when I mean patience, it has taken me up to 5-10 minutes to slowly work out a 1.6mm screw.
I commonly use this method in my shop when a first-time 'do it yourself'r' brings in an iphone that they intended on replacing the screen (after watching that cool youtube video), and right off the bat strip the pentalobe screw with a philips head. 8-
This is always a last resort, but, over the years I've found it effective.