Another nice thing for these agencies is that being on facebook already indicates certain things about you(as does not being on facebook). I know for a fact tha

Another nice thing for these agencies is that being on facebook already indicates certain things about you(as does not being on facebook). I know for a fact that here in the Netherlands, during a standard security check, our intelligence agency checks if you do or don't have a social network account. If even 'regular' security checks take this into account, then I'll bet you dollars to donuts that it's certainly looked at when they suspect you of something, or as dragnet profiling/surveillance.