I just watched a news report on this kind of device for police officers last night. Here's the link:
http://www.cnn.com/2010/CRIME/04/16/police.head.cam/index.html
In theory it's a good idea for police to have these, iff the video is available to the general public. Otherwise, the police could lie about their own actions and only show evidence against others. Then again, right there in that video, they show a female police officer chasing a drunk man on foot and using her taser on him for seemingly no good reason. He didn't seem to be physically resisting arrest (other than the running) and was not a threat to her, yet she tased him and they're showing it on a news report like it's no big deal or standard procedure or whatever. The fact that it's on a news report and there's no backlash against that use of a taser is a bit disturbing to me, personally.
Anyway, yes I think personal cameras are a great idea for several reasons. If more people start wearing these and it becomes more normal and accepted, then maybe, just maybe societal norms will change and less people will get hassled by authorities for taking pictures or recording video in public
