[huggah]

The display in Glass is incredibly unobtrusive. Glancing at a direction arrow (for maps) is no more distracting than glancing at the speedometer--it's less distance for the eye to cover, and the displayed images are ruthlessly simplified so that absorbing them is almost subconscious.

I think the danger comes from people who get text messages while they're driving and want to look at a shared photo. That should be disabled while driving, which glass can make a pretty good guess at.