title: Wifi connection doesn't stay alive when asleep, with iOS4
body: <p>Knowing that iOS4 support wifi stay alive in asleep is really happy thing. However I got some different experience:
  I've got 2 iPods, iPod 2nd gen &amp; iPod 3rd gen. Both updated to iOS 4 beta. iPod 2g can stay wifi on in sleep while iPod 3g always disconnect wifi in sleep. I ping both of them while they're in sleep mode, only iPod 2g keeps reply echo.</p>
  
  <p>Could any often a hint to show the point I'm doing wrong?</p>