The only place I've heard this is on TWA - they made a huge deal about it .. "FAA requires that window shades be in the up position for takeoff and landing for safety reasons"... I can't figure out a single way this affects safety - what, they want to be able to look in the windows if you crash? They could probably find a big hole to look in instead
So if the FAA requires it, why am I not hearing this on other airlines? Which airlines have you heard this message on?