There's been a rash of nightclub shootings lately and even if it does validate our anti-social dive bar tendencies, the San Francisco Entertainment Commission is under a lot of pressure to put a stop to nightclub violence.
As the Examiner reports, the Entertainment Commission is investigating various technologies that would record information from each patron's ID and allow the staff to make notes of any unruly behavior. SFPD recommended scanning everyone at events with more than 100 people and storing the info for at least 15 days. If a rowdy patron is kicked out or moves on to another bar, the next bouncer would have that information available. Just think of it as Foursquare meets a reverse-Yelp and you check in with your Clipper card. (Perfect analogy!) Except you don't get to be mayor, you just get blacklisted for being a terrible drunk.
Of course, the whole thing is rife with privacy issues, so we'll see how far they get once they start putting legislation down on paper.