Ideally it will only record when you tell it to. I don't really see this as any different than what smart phones already do. Yeah, it's somewhat easy to accidentally record your actions/location/whatever with those already and this would make it even more convenient for you to do something silly, if you're careful, then it's really not any worse than what we're already dealing with.
It's not the technology so much that makes it bad, although the companies make it way too easy to do bad things with them. It's just that people need a lesson in what exactly is private information. If social networking has taught us one thing, it's that people tend to be blabber mouths, they want to talk about everything and anything and if you give them an outlet that even presumably is being listened to, then they'll tell everything.
Yeah, it can be kinda scary how much of ourselves we're putting out there, but honestly, this... sort of thing, at least... is what I've been dreaming of for years. Personally, I was hoping for a terminal prompt and a (virtual?*) keyboard, but the times they are a changing in this touch screen world.
*Yeah, I wanted to be one of those idiots that would stand there staring off into space typing on absolutely nothing. To me, at least, it seems a lot less silly than talking to yourself. "Tell me how to get to George's deli." and people looking at you funny when they think you're asking them out of nowhere. Even when they've been around for years now, bluetooth headsets still seem a bit odd and confusing if someone walks by talking and I'm not sure who they're talking to.