As CBS News Correspondent Jim Stewart reports, this one is approximately 50 minutes long and is of "exceptional audio quality."
The Islamic news agency which obtained it quoted bin Laden predicting his own death, saying: "Surely this year I will lead my steed and hurl it, and my soul, at one of the targets ... and I become a martyr."
U.S. intelligence officials said they had heard of a second tape but could not confirm it is bin Laden. Like a shorter tape released Tuesday, the longer one also appears intended as a morale booster for the scattered al Qaeda forces.
"He's obviously raising the confidence of his people. He's obviously exhorting them to do more, and whether this is a signal of impending attack or not is something we're looking into," says CIA director George Tenet.
Officials still aren't sure how bin Laden slipped away from the Tora Bora mountains last year, but believe that ever since he's been in hiding with a small group of bodyguards and couriers along the Pakistan-Afghan border near Karachi. Second in command Ayman Zawahiri is believed to be with him while the top operational leader, Khalid Sheik Muhammed is on his own and constantly on the move.
Analysts said bin Laden's voice in both tapes sounded healthy, firm and rested but point out that for the third time since fighting in Afghanistan sent him running for his life he chose an audiotape instead of a picture or video to communicate with the world.
Why? Perhaps, analysts suggest, it's because he has shaved his beard, cut his hair and otherwise changed his appearance to avoid being recognized. Or maybe, they suggest, because he's wounded.
He certainly has good reason to be cautious. Three of his top lieutenants have been captured and a team of special operations forces, CIA and FBI agents has been steadily squeezing the area he's believed to be hiding in.