Id imagine that Google Glass will fall under the same laws banning cell phones and electronics while driving so Im not so sure how much potential this has besides putting the ability to unlock your car on Glass.
It'll really come down to officer judgment, since they can also view it as hands free (like a Bluetooth).
In regards to this app though, it doesn't appear to serve any function while driving, so I can't imagine it being used during driving.
That's usually the stated justification, but in reality what gets banned is pretty much completely unrelated to the empirical evidence as to actual sources of distraction; most places explicitly ban non-hands-free device use, even though, IIRC, studies have shown that hands-free and non-hands-free device use have similar effects on driving ability (and that using a phone, hands free or not, has similar impact on driving ability to carrying on a conversation with a passenger, which is also not banned.)
If there's any justification for the actual bans we see , is that there is an industry wants to sell in-car hands free devices and hands-free add-ons for devices