Through the magic of technology, this post at CrissCrossed.net from January just popped up on my radar, covering examples of using the one-two visual and data-rich impact of maps for activism. His examples cover pollution reporting in China, community mapping in Brazil and others. Add to that the Ushahidi-powered BP Oil Spill Crisis Map and of course the gamechanging effects of incident reporting and crisismapping in immediate the aftermath of the Haiti earthquake, and you have a sea-change in the ability to respond to a problem with geographic dimensions quickly, and with data-driven, crowdsource-able maps. This ability is largely thanks to the work of Ushahidi (which now even supports remote reporting via voice calls) and projects like Open Street Map.