Not saying glass is a bad thing, I think it's really great. Just wonder how (or if) this is going to affect the road safety.
The sort of person who would use something like Glass to use GPS or a HUD (speedo, tach, clock?) without taking their eyes off of the road will likely be a more safe driver. HUDs have been credited with enhancing aviator safety; this could bring such innovations to the road.
The sort of person who looks for distractions anyway will now be distracted by Glass. I'm not sure if this will constitute new distractions or a new way to consume old ones, though.
Generally the more crooked the police department, the more violently they react to being filmed in action. Where I live they're fairly lawful so they kinda laugh and/or cooperate (pose for the camera, would your kids like some free baseball cards, etc). On the other hand, there are less civilized places on the coasts where you'll get pretty well beaten and jailed and your camera destroyed if you film corrupt cops, even if by some miracle they're not breaking the law at that moment.
Aside from corruption, this is going to be a pretty big issue for "drive by recording", both sides of every little drunk driving traffic stop and minor fender bender (oh and worse situations too) will probably want your recording data, even if its just a few seconds outta the corner of your eye. Even if its a complete waste of time, if its a high enough crime you'll have the criminal system going bonkers with you in the middle. I could see this affecting road safety in a self censorship manner. Oh no a crash, better not look that way or I'll get dragged into court as a witness for the zillionth time, whoops just crashed into the ambulance that pulled out while I was intentionally not watching the accident.