It's not uncommon for controversy in video games to bleed over into the real world. After all, you have these partially insane lawyers saying that video games are "murder simulators", and as a result often games are pointed at as an inspiration for violence. Hence, it wasn't surprising at all to see that in Chicago, advertisements for Grand Theft Auto IV have been pulled from city buses, following a fairly violent weekend.
Local citizens were concerned that the advertisements were doing nothing to help a nasty problem. Personally, this actually seems like a good thing. The police are citing the increase in violence as due to warmer weather towards the summer, not video games, but angry anti-gamers would likely use any excuse they could. Even though the ads themselves contain nothing that could incite violence, their mere presence might spell trouble for Rockstar who has already faced numerous PR issues with their games.