I confess that in 2000 hours of PIC I have NEVER turned my phone off, or put it in flight mode. NEVER. I've never heard the old cell phone interference noise - I think that probably went away when 3G was introduced. Usually it just sits in my pocket, occasionally I will use it to text someone and say I'm arriving. At normal GA altitudes it generally works OK.
As for airliners... now they have picocells on board it's a bit hard for them to argue that the plane will fall out of the sky if you turn your phone on. A, ahem, good friend of mine, has been known to use FlightAware on his phone in flight to figure out where he is. He says it's hard to get good GPS reception sitting inside a metal tube, but if you hold the phone against the window for a couple of minutes it generally works.
I remember reading years ago Matthew Parris (well known UK journalist/ex politician) writing that he always keeps his phone switched on in flight on the principle that someone is bound to, so it may as well be him.
As for legality, in the US anyway, it's at the pilot's discretion. So if I'm the pilot, I apply my discretion and keep it switched on.
As for keeping things available - not just in small planes either. Since BA038 and the Asiana thing at SFO, I keep my wallet, passport and phone in my pocket during takeoff and landing, always.