i got openandnotorious.org to map out abandoned and foreclosed properties, where nodes placed in these locations would turn into a legally recognized easement surviving new owners after 5 years under California law under the doctrine of adverse possession (for easements). The legal requirements for possession during this period include other factors, but the main ones are that the use be open and notorious. While proving that may otherwise be difficult, being listed on openandnotorious.org would solidify the presumption. 
 

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http://lists.hackerspaces.org/pipermail/sudoroom/2012-May/000240.html
Dear Sudo people. I had the wonderful opportunity last night to talk to Brewster Kahle (http://brewster.kahle.org/about/) of the Internet Archive (http://archive.org/) for a long while about the emergence of Oakland's tech communities and of our activities at Sudo Room, Oakland Local, and Tech Liminal. [Susan - he told me to pass along his warm regards.] I was psyched to learn that Brewster has been making serious efforts to enable open WiFi across cities & neighborhoods in the Bay Area (& elsewhere). There's some coverage of his initiatives in connection to San Francisco housing projects (http://gawker.com/373658/brewster-kahles-internet-archive-brings-broadband-to-sf-housing-projects) and more recently on our side of the bay, in Richmond (http://richmondconfidential.org/2011/10/10/archive-org-founder-talks-free-wifi-with-richmond-officials/). I shared with him some of our initial discussions about solar powered WiFi routers providing public access to the Internet from the top of foreclosed and abandoned properties around town. I even took him through the 5-year adverse possession plan to get easement property rights to keep them there permanently. He was intrigued and most importantly gave a strong indication that he would like to support our efforts and particularly in helping create the backbone across Oakland that would facilitate mesh networks. As a first step, he suggested that we map out 25 or so of the taller buildings around the city that would allow us to put some antennae equipment on their roofs. If anyone is interested in working on the project and/or sharing their thoughts about it, that would be hella great. -Eddan