Maybe you don't want all of your high school pals to know where you are. Maybe you don't want your boss/mother/spouse/stalker du jour/nieces and nephews and other random peeps to know where you are.
Click for Valleywag's instructions on how to disable Facebook's location based tags. I might be kind of a buzzkill at parties and blogger events, but I'll feel safer and my clients won't know I'm out partying when I should be working. ;-)
Think I'm paranoid? Check out Please Rob Me.