sandblaster wrote:
Even if you leave the phone plugged into the charger and on wifi, the phone could still revert to cellular data if your wifi drops, so the best way to ensure no cellular data is consumed is to either turn celluar data or the phone off.
While this is certainly true, it's pretty unlikely. I've had three iPhone4s in the house for 18 months now, and every night they're on the chargers (and connected to wifi) with nary a blip of usage. Perhaps that's due to my 99.99% uptime (yay, comcast business class and decent SOHO wifi gear) but for most people it's sufficent to just plug the thing in at night if you want to stay on wifi.
