That was a really interesting theory, especially since I remember the news people saying "There was an explosion on tower 2..." and I remember thinking that was a weird way to describe what happened - planes flying into the buildings THEN exploding. The way they said it is as if they didn't see any airplanes.
But aside from that, I looked into this "No Planes" theory, and its been debunked on several levels. It seems to be a "false flag" as well, with the intent of discrediting the real Conspiracy investigations.