People are using Facebook & Twitter to alert others of DUI checkpoints.

Police are sometimes accused of linear thinking, especially when it comes to DUI checkpoints.
They set them up on Friday and Saturday nights. They redouble their efforts on New Year's Eve.
Perhaps the finest example would was one police force in the wine country of Northern California that decided to put a DUI checkpoint at the bottom of a winery's driveway. Yes, on barrel-tasting day.
The police now have a stronger enemy in the people -- the people who are using social media to warn others that this particular Friday or Saturday night has been selected for special drunk-driving checking.
At first, it seems that police were a little bemused by the very idea that people wouldn't want other people to be caught be the police.
Now, however, some police forces have decided to use more sprightly tactics to ensnare those who are unwise enough to imbibe and drive.
As the Associated Press reports, big checkpoints may be on the way out.
They're too obvious, take too long to set up and word travels too quickly, as they're so often located on busy roads -- on the shooting-fish-in-barrel principle.
Some police forces say they are using roads less traveled and even setting up in the middle of the week in order to catch their quota.
The AP quoted Barbara Harsha, executive director of the Governors Highway Safety Association, as saying: "Social media cuts both ways. It can be a good tool to inform the public about what's going on, and it also can be used to undermine enforcement efforts."
But is informing others on Facebook and Twitter that the police are out in force truly undermining enforcement efforts? Or does it, in fact, show a peculiar form of solidarity that isn't always evident in other aspects of social life?
http://news.cnet.com/8301-1023_3-57579508-93/how-facebook-and-twitter-mess-with-dui-checkpoints/