[ippisl]

And what if if stand a few meters from a google glass user and don't see the led?

[Retric]

You can easily pick out the recording LED on camera equipment from 30m so that's not really an issue. The bigger problem is simply not noticing once glass becomes even slightly popular.

[jamesaguilar]

Or what if said glass user has heard of electrical tape?

[ippisl]

Or even a bit of paint, done nicely.