When Osama bin Laden issued his videotaped message to the American people last month, a young jihad enthusiast went online to help spread the word. America needs to listen to Shaykh Usaamah very carefully and take his message with great seriousness, he wrote on his blog. America is known to be a people of arrogance. Unlike Mr. bin Laden, the blogger was not operating from a remote location. It turns out he is a 21-year-old American named Samir Khan who produces his blog from his parents’ home in North Carolina, where he serves as a kind of Western relay station for the multimedia productions of violent Islamic groups.