The New York Times had an article yesterday. Seems when the police arrested demonstrators at the 2004 Republican convention there were lots of video cameras rolling. In some cases, the police testified to one thing (demonstrator resisting arrest) and the tape shows another.
Reminds me of David Brin's book, The Transparent Society. One of the paradoxes is that by depriving bureaucrats, like the police, of privacy during their work hours, we can protect values, like not convicting people of crimes they didn't do. The same principle can apply in many places. I'd argue that it could be beneficial to collect personal data, so long as the database and its use were totally transparent. More in future days.