What happens if your cellphone is on during a flight?

Modern smart phones, Blackberries included have features that automatically switch on and off. So what might happen if one goes on a flight and doesn't disable the auto-on feature? Well first and foremost it is a safety violation, so we don't do such things. But if it would happen? Then you would pickup SMS from Telcos of countries you fly over. Countries like Ukraine, Belorus, Poland etc. So you get a free log at what time of the journey you reach what network. But as I said: we don't do such things.