Worried about ever growing bans on Google Glass, Google publishes 'how not to be a Glasshole' FAQ.

[Orrex]

46. Probably not if it's inadvertent.

I mean, maybe if you were riding through someone's yard, but if you're riding in a public space and you happen to snap something as you pass, then that's probably fair game. I have to disclaim that this isn't a legal definition but is rather a matter of aesthetics.

In a broader sense, the proliferation of cameras can be argued to make citizens comfortable with constant surveillance, so that's problematic in its own right. I'm not naive, though, so I see the spread of cameras to be more or less inevitable, but there are still matters or privacy to be considered, and it's probably better to consider them before we look back on them with nostalgia.