Looks like this has been going on for far to long already but thought I would put in my 2 cents. Most people here are raving against taking a stripped frame locked to the rack on moral grounds. Fair enough but I would like to point out that there are actually city ordinances in some areas that prohibit leaving a bike locked to public rack for an extended amount of time. This is common on college campuses where abandoned bikes can become a real problem. Those bikes take up space which is needed and become and eye sore once they are stripped down and rusting. So around here if you leave your bike locked some where for a long time the authorities will make a note of it and they will later take your bike impound it and then sell it or give it away. So I don't think taking an abandoned bike frame is a serious crime that anyone should get all fired up about. If the owner had any respect for their belongings they would come and take care of it properly.

Also you should not be using a hack saw since that is doing it the hard way.