If Craigslist actually stood by their community-centric, "everybody share" principles, rather than wear a fake mask of anti-corporatism over their money-grubbing true face, then Craigslist themselves would put a single checkbox on every Craigslist post form letting the user make that choice. And the default state of that checkbox would be "yes."

Then CL could just offer a bare-bones, REST, read-only firehose API to access those posts. Just like how Twitter does it. This entire project would probably take the developers at CL a month to roll out into prod. Hell, knowing how software shops work, they probably already have 3 private internal versions of it that were shelved by the ignorant, risk-averse management who only fear change and don't know how to tread water in the meandering river of technology and Internet society.

Wild idea for the Techcrunch rumor mill in 2011: it's too bad Twitter doesn't buy or merge with CL, and in absorbing CL, make them be more open and community-centric.

Perhaps CL will see the light and open up an API, as the newspapers get more desperate and turn up the dial on the hate. CL is going to need to show off something, anything to take the spot light off themselves before the wolves rush in now that they're injured & bleeding.