I remember clearly in Abu Dhabi that you had to power on all electronics or they would be confiscated. The reason I remember is because my older iPad charger I forgot so it died. Thankfully a friend has a charger because they said I wasn't getting on without it powering up.
Also they take the no photos very seriously. A friend took some pictures of the guards dressed in white and instantly they confiscated the camera. They begged and pleaded and were given it back only after deleting the pictures with a severe warning to not do it again.