About a year ago I left my phone on while flying on two planes since I had a layover. First off, I can confirm it does connect, even on 3G since, while I was landing in Toronto, I pulled up google maps on the iPhone which then downloaded the local map to where the phone had never been and then showed me where the plane was flying above on the ground through the GPS. I was able to find spots I recognized only cause the GPS let me know where I actually was as I watched it track our landing.
The more important item of interest though is this, a cell phone antennae is omni directional (every direction). Turning your cell phone off inside a plane does not prevent cell phone signals from being in the plane since the cell phone towers which are communicating with as little as one phone that is not inside the plane, those towers are broadcasting in every direction. Cell phone towers don't know which way a cell phone is (remember it takes 3 towers to find a position through triangulation because one tower doesn't know). Because the tower doesn't know then, if someone is standing on the opposite side of a cell tower from an airplane, the airplane is still receiving the cell towers data and depending on the position of the phone then it is receiving the data from the phone to. The only rason a plane would not receive data from a cell phone outside of the plane is the plane is further away then the signal strength can reach and if a phones signal strength reaches a cell phone tower then it's pretty powerful already. A plane has plenty of windows and is therefor not a Faraday cage or even close. If cell phones were a hazard to planes then there would be no cell phone towers anywhere close to an airport at all.
I heard this once, but this may just be an urban legend, but I heard that cell phones aren't allowed during takeoff and landing because for some reason or another they don't want people in the plane communicating with people outside the plane. I don't know if this is true or not so take it with a grain of salt but the notion had to do with, if there is an emergency in the plane, we don't want you calling someone outside the plane and letting them know (which will likely lead to the news finding out if it's a panic situation) and vice versa. If there is an emergency on the ground, they don't want people inside the plain to find out causing terror which would spread to everyone on the plane in short order and create another bad situation so yeah. Again, this may be an old wives tale. Take it with a grain of salt but, if thats true then it does make sense. See the movie Die Hard 2 ;)
