Consider what it means to be in public. If you are in public you are giving up your implicit right to privacy relating to being viewed or overheard (and depending on jurisdiction, recorded without permission). I would argue that it is perfectly reasonable for the government to have as many cameras as they want in public spaces, with a few caveats:
* The data from the cameras should be publicly available. Probably not in real time (or with the option for the temporary disabling of real time by law enforcement until after whatever they disabled it for has ended (with obvious common sense restrictions, like maximum 48 hour delay)).
* This would require changes to laws, and society, about how illegal certain types of information is (information should not be inherently illegal) because anyone would be able to put anything on the public cameras, and to prevent cover-ups the data must always be there, even if horrendous and despicable (see: child rape, which is then child porn).
* The government has to respect the privacy of private property. Obviously businesses (with public areas) may prefer the government to invade their privacy for the protection they get. But people should be able to request movement (or removal of areas being recorded) of camera's view.
People will have to accept that being in public means potentially being recorded, and laws must adjust to fit that. There isn't a way around it if we like being able to take pictures, and recording ourselves. Other people will become recorded. Allowing the government to do it is a logical legal extension.
Consider what this enables, and what we already have which mimics it, by accepting this we acknowledge the reality, and don't deny what can already happen. And then consider what this enables that we already don't have. In the end public cameras are just another piece of automation:
* Following people's movements, and interactions, in public areas. We can already do this by tailing people. However currently it requires quite a lot of man power to do it (governments or corporations). With cameras anyone can do it, with some facial recognition software it becomes completely automated. You or I can see where any CEO goes, who they talk to, etc. Of course it can also be done to stalk people more easily (not that it's currently hard).
* Recording people's conversations in public areas. We can do this with a directional microphone, or a well placed bug.
* Every violent crime committed in public is easy to solve. This is reason we are installing them in the first place. We can't do this currently. But with this we can make it so it applies to police officers as well.
* Real-time world analysis. The start of Ubiquitous computing[1]. We don't have this at all for now. We can tell where there is heavy traffic. Follow a protest. See the weather at an exact location. I'm sure some startups could do great things.
So the next time you call your congressman, or discuss issues like this. Consider offering the compromise of making the recording public. It can also allow you to bring up the issues of illegal information (for example illegal primes are a good example of why it's ridiculous) or that there is no expectation of privacy in public.
Besides it would give us a good excuse to have punk hairstyles (http://cvdazzle.com/).