Here's a picture of a stamp recently found on an envelope at Bin Ladan's house. This picture clearly explains where Bin Laden got the idea from..

And, this phone conversation between George Bush and Saddam Hussain is sent by one of the readers in reply to previously published conversation:

Saddam's Phone Call to President Bush on Sept. 11
Saddam: "President Bush, I would like to express my condolences to you. It is a real tragedy - so many people, such great buildings. I want to assure you we had nothing to do with that - it was not us."
Bush: "What? - What buildings? What people?"
Saddam: "Ummm...what time is it in America now?"
Bush: "It's 8:00 in the morning."
Saddam: "Ooops... Sorry I'll call you again in an hour. Bye."