The most interesting posters started appearing on certain bus stops throughout San Francisco on August 31st. Mind you, the San Francisco MTA has a policy against ads that “appear to promote the use of firearms.”

The posters were a joint effort of the Second Amendment Foundation and the CalGuns Foundation. More here and here. A clearer picture of the poster can be found here. The poster is an adaption of an earlier poster by Oleg Volk.
UPDATE:Â According to a CBS News blog, the SFMTA is investigating whether the posters above should have been allowed to be posted at bus stops in the first place. The feeling I get from that report is that the MTA has been getting a lot of pressure from the San Francisco Board of Supervisors to remove the ads.
If they remove them, Alan Gottlieb will be one happy man. He has vowed to sue if they are removed and it sounds like he is just itching for the chance to sue SF on First Amendment grounds.