Twitter has caught some flack in other countries for giving accounts free reign on what they can tweet. Twitter responded that it'll adjust its policy to include the ability to censor tweets if a country demands it to. We just might see Twitter's first high profile case sooner than later because Brazil just sued Twitter for allowing accounts to tweet where DUI checkpoints are.
The ramifications, to us US citizens, are selfishly small but could mark as the tipping point when other countries start to take control of Twitter in their countries. The accounts in question (namely LeiSecaRJ) use Twitter to publicly share the locations of radar and DUI checkpoints so people following the account (near 300,000 twitterers) can avoid such stops. Brazil is predictably unhappy with such accounts because of their use in avoiding the police (and possibly promoting driving while drinking) and has sued Twitter and the accounts for a $290,000/daily fine.