I first read your FR home page several months ago. VERY well done. I just wish everyone knew this stuff, especially our politicians.
Ahmadinejad and his ilk believe in things so far removed from most people's beliefs that they simply cannot comprehend someone like him. Which means they simply cannot comprehend the threat he poses.
Personally, I do not think he is bluffing. He has something planned for the night of August 21/22, or the day of August 22nd. What it is I do not know.
Perhaps it will be a nuclear test announcing he has joined the club. Or, he could decide not to "waste" a bomb testing a design he got from Pakistan and knows will work, and just use it immediately against Israel. It could be something more mundane, such as a biological/chemical warfare attack.
Whatever it is, I doubt it will be something as mundane as blowing a dozen airplanes out of the sky. He has built expectations up too high for something that "routine" to fill the bill.