I'm not an explosives expert, but maybe someone who is can comment on the plausibility of this? It seems like an ipad or laptop couldn't carry enough explosives to take the plane down.
You don't need to take the plane down, causing enough damage will suffice (think sudden decompression).
That said, I call bullshit on this one. At least here ("Large European City", second airport in the country traffic wise) they always ask you to power on notebooks, tablets and even cameras to verify that they're real. Heck, I even had to turn on my camera and let the man wave his hand in front of it to check that it was actually his own hand showing on the display!