Seems that it all depends on the TSO. I had an issue with one this last weekend because my iPad, SLR, extra lens, and binoculars were all in one bag - he said the bag was "too dense" and totally unpacked my bag into two bins to re-run through the x-ray. He let me know several times that in his opinion iPads should always be removed from the bag because they had a "huge power supply."

He didn't think it was funny when I told him I suspected he just wanted to see if I could repack my bag..... Humorless sort, he was.

Only one other time have I had anyone make me take the iPad out of the carryon bag.