I'd be interested to see interaction studies in the non-tech community about Craigslist, because I haven't seen a person in non-tech find difficulty in posting on Craigslist.

Also, don't confuse my opinions about Craigslist's design/UX with an opinion on the case. I've used Padmapper extensively. While I believe that Craigslist has a right to do what they please with their content, I don't see what Padmapper was doing as wholly legally wrong.