I got a chance to play briefly with IFTF's new Google Glass device (see accompanying photo). Some quick notes:
As the photo illustrates (and as the manual apparently states), Google Glass devices do not work with regular eyeglasses. Unfortunately, despite my nearsightedness, the test on the screen for the Glass display is set in a way that left it illegible for me without my eyeglasses. (I suspect that the image is projected in a way to be legible while your eyes are focused at a distance.)
Since it uses a bone-conduction mic & headphone, it wouldn't be a simple task to just stick a Glass unit on regular glasses.
The voice control works reasonably well, and I was able to instruct it to take a photo (I'll link to it when I get access to it).
The voice control doesn't work perfectly, and was confused by terms more complex than "take picture."
The voice control is speech recognition, not speaker recognition. It responded to accidental commands from the person I was speaking with while testing them.
This last is the biggest risk factor for abuse. Saying "OK Glass Google [something shocking]" when someone is using Google Glass in near proximity will make it search Google for whatever startling content you've given it.
Not that I would suggest any such thing. Nosiree.