Well, this did not take long.  Facebook Places has been out for a week or to, and already an enterprising individual has hacked together Nearby Friends, a mash up that enables you to see where those in your FB graph have recently checked in.  The interesting and scary thing is that it can also track where you have checked in over the recent past, thus putting together a trail of your check ins for all in your network to see.  Once again, Facebook has set the bar that much higher for complete disregard for everyone’s privacy.  Here is a good article on ReadWriteWeb to help you manage your privacy settings related to Facebook Places.
Via RWW