Well, it doesn't list Piper's Orchard at the South end of Carkeek park for one, so that alone would make me tend to question its accuracy.

@1 Actually, it does! Or did you add that listing?

http://fallenfruit.org/

Very popular in LA

http://www.knoxgardner.com/ a group in the Judkins Park niegborhood gleans plum trees from various backyards (the Italian immigrants who built the neighborhood planted WAY too many of this highly invasive species of fruit tree).

If you're interested, sign up for Knox's email blast when neighbors get together and send surplus off to the food bank and various canning projects.

Also if you are into urban foraging, http://firstways.com/ these people are based in Portland, they have all kinds of weird fun facts and techniques for gathering, trapping, processing woodcraft products in the city.