flynn23 wrote:
] Has there been a documented case of abuse with these tools
] yet?

The matter has been widely studied, particularly in Canada where there is a legal requirement to study privacy impact of new legislation.

Here is the ACLU's page: http://www.aclu.org/Privacy/Privacy.cfm?ID=13482&c=130

Privacy International also has a number of links. http://www.privacy.org/pi/issues/cctv/

The Norris and Armstrong studies are frequently referenced. The ACLU has one here:
http://www.aclu.org/Privacy/Privacy.cfm?ID=13550&c=130

Quoting:

Three out of ten people were surveilled for crime related matters, two out of ten for forms of disorderly conduct, but the largest category, nearly four out of ten were surveilled for ‘no obvious reason’. This was echoed when we examined the basis of suspicion, with only one quarter of people subject to targeted surveillance because of their behaviour. ...the most significant was categorical suspicion where people were surveilled merely on the basis of belonging to a particular social or subcultural group.

Other sources:
http://www.caslon.com.au/privacyguide20.htm
http://www.oipcbc.org/investigations/reports/invrpt12.html

RE: Nashville Police to install city wide video surveillance system.