As regards responding to police violence on demonstrations with passivity, peaceful resistance or an organised response of resistance, I personally think these questions are tactical considerations and not issues of principle.
Passivity combined with detailed recording of the events by legal observers and plenty of filmed evidence was certainly a successful tactic as deployed by the Climate Camp. Of course this success came at a price - many peaceful demonstrators were terrorised, bruised, battered and someone could have been killed there. For Ian Tomlinson at the RBS he was assaulted and subesquently died just because he was there. So non-violence has not deterred the police from violent attacks on demonstrators. It has however, assisted in winning the war for hearts and minds.
However, on other occassions there are other tactical considerations. The Tamil protest yesterday was non-violent but did manage to forecably push through police lines to occupy the streets and in sufficient numbers to ensure they could not be moved without the deployment of violence on the part of the police (something the police for obvious reasons were unprepared to do at present).
At some point I suspect that progressive change will be resisted by armed force on the part of the state - not just battons but whatever is deemed necessary to quash a movement. If the rich and their state felt that their very rule was threatened there are no real limits to the violence they will contemplate. At that point public opinion and strength of numbers may be on our side but the state may still resort (would be likely to resort) to significant violence. In which case mere passive resistance will not be enough.
In the meantime, too much concentration on street fighting tactics in response to police violence can be counter-productive. It could deter the majority of the public who are not up for violent confrontation from joining protest movements (this is one of the reasons the state provokes violence). A violent response from the protesters (and I have always defended those who are moved to fight back against police aggression) can provide amunition for the distorted press coverage we are used to and make it easier for the police to increase their violence.
Instead we are now - right now - at a point where it is becoming harder for the police to violently assault peaceful protests. We should seize the time to push our advantage. Continue to video record every protest, insist on our right to march. Resist attempts to kettle where possible through passive resistance. More and more people are showing a willingness to get involved in pressing for change in response to the environmental challenge we face and the economic crisis capitalism faces.