Almost all non-iPhone phones come with what I would argue as a pretty effective such 'kill switch' device -- a removable battery.

Or am I seeing an insufficient number of daggers in the shadows...? I mean, I figure Google and the NSA already know me better than I do, and I don't really care, because I've nothing to hide and I don't feel like being afraid all the time. Oh -- and I think that "having nothing to hide" is a very good security policy.