title: Finding trips in a set of waypoints
body: <p>From a set of waypoints, each with lat/lon and timestamp, how do you find out the start and end point of a trip vs. staying at a place over time? </p>
  
  <p>I'm playing with Google Latitude data, unfortunately it only provides a stack of locations, no meta data. I tried to calculate the average velocity between waypoints, but because of the nature of Latitude sometimes location data gets slightly inaccurate and it looks like I stopped somewhere even though I was still on a trip to somewhere.</p>