Yup, property destruction is taken as a given now among most activists. I did a panel discussion on this topic several weeks ago at American University with Nadine Bloch of DAN and Michelle from the Plowshares. The audience seemed to be mostly into PD, but several had qualms about the black bloc. This wasn't surprising given that the event was sponsored by the Washington Peace Center.
For a good graphic on "to brick or not to brick" see: http://www.infoshop.org/img4/life_is_short.gif
Chuck0