If it wasn't already clear that Twitter wants to keep police and spies out of your tweets, it is now. Twitter is warning developers that it won't let them use public programming kits or Gnip data for surveillance reasons, whether the clients are law enforcement or anyone else. Just because many tweets are public doesn't mean it's acceptable to harvest them, Twitter says. To that end, it's promising "expanded" efforts to crack down on developers who use the data for surveillance reasons. Get caught and you'll either have limited access or lose it entirely.