So you've purchased a cellphone with microphone, video camera and GPS capability. And you've also purchased an extremely high-powered computing device to play games on that, coincidentally, has high-powered voice-processing and surveillance capabilities (e.g. Xbox360 w/kinect). On neither of these devices do you have admin/root privileges. And both of them have been shown to connect to their "home" manufacturers/owners and send back data periodically.
So... suppose law enforcement decides to publish their Top 10 Wanted to both of these manufacturers with the understanding that all capable devices will periodically scan for known voice patterns and/or facial patterns and report back findings. Nothing technically impossible about this.
So... once it becomes ridiculously cheap to store this data... why not scan continuously under the guise of "homeland security"? Characteristics can include people with long beards, dark skin, particular languages, what-have-you.
But you may be thinking... "I have nothing to hide. If a company is willing to buy me a camera/game/etc they can watch me all they want." Recall... there's a difference between having nothing to hide and having nothing to show.