Bet ya if your phone was locked down in the typical corporate IT security way (pattern lock is out, need to use a numeric pin, it needs to be at least N digits long, entered correctly before you can do squat with the phone, gods help you if you screw it up too many times), you couldn't.

There's also startup time once you've launched the app. Even on a modern iPhone, that's a second or two before the shutter iris goes away and presents you with the viewfinder screen.

The Glass demos I've seen make it instantaneous.