title: iOS 4 periodic location updates using GPS while app is in background
body: <p>Is it possible to have the phone power up the GPS every say 30 minutes and get the user's location while the app is in a background state?</p>
  
  <p>The significant location change service is a little too unprecise for my needs.</p>
  
  <p>I am trying to track a phone at all times without killing the battery life too much. Any suggestions are more than welcome!</p>