I've been in more than one argument about our surveillance state, where my opponent supports public surveillance cameras, has claimed "you only need to be scared of them if you're doing something wrong. This, in my mind, opens up the argument to hypotheticals, my favorite being, "what happens when the government wants you to install them in your house?" My opponents inevitably then claim it will never come to that.
One thing I know? Never say never. Because in England, the highest ranking police officer just suggested people install them in their houses. England, for those not in the know, has been miles ahead of America in terms of public surveillance. The town of King's Lynn even brags about having the first public spying program in the country.
Undoubtedly, these can be used in very real ways to help in the fight against crime. My problem, however, is it's only a short leap to using these to serve private (rather than public) agendas. Also, I don't trust the security of their computer systems. Also, while I am in many aspects a liberal, I don't trust the government enough to say, "hey, feel free to record every aspect of my life!"
Again, don't make me agree with the libertarians.