I'm convinced that Google Glass will fail for this exact reason. People really don't like being recorded. Even though surveillance cameras are widespread, it's much more personal when you can see the person recording you.

All it will take is one creepy app for Google Glass and people will start to revolt. Imagine an app that has a large amateur porn database that does facial recognition on people around you and displays naked images of similar looking people. Obviously that would be an incredibly hard software problem to get working well, but it doesn't have to work well; in fact it doesn't have to work at all. All that is needed is a single article about it in the press and it will take off.

I imagine that a very loud privacy vs free speech debate is imminent.