If I hadn't sold the iTouch I got when I bought my macbook I'd deffinatly do it, but my iPhone is my life and I'd hate to watch it bouncing down the road in my mirror.
I know this is an old post but to protect your phone use life proof case for you phone. Its water, sand ,snow proof. Then purchase the bike mount by same company. I'd bet with life proof case on the phone would survive if it fell off at 70 mph. I believe Gauge Face also works with other smart phones.
mounting a smartphone on your handle bars just screams "nerd" and it just looks stupid, kind of like a pocket protector,, and to think people callled me nerd for putting a tach on mine. Harley has a tank mount pouch for smart phones that atleast looks much better,