According to the Associated Press,
After bin Laden was killed in a raid by U.S. forces in Pakistan, senior administration officials said the body would be handled according to Islamic practice and tradition. That practice calls for the body to be buried within 24 hours, the official said. Finding a country willing to accept the remains of the world's most wanted terrorist would have been difficult, the official said. So the U.S. decided to bury him at sea.
Soon enough we will learn more details of how this unfolded: Was the body cremated, tied down with weights (you certainly wouldn't want it to wash ashore)?
Burying one's enemies at sea might seem a bit strange, but it has been done before. After Adolf Eichmann was convicted of war crimes in 1962, the Israelis first cremated the former Nazi official and then scattered his remains over the Mediterranean. Likewise, following the Nuremberg trials, the remains of Joachim von Ribbentrop, Ernst Kaltenbrunner, and others were cremated, then dumped into a ditch in the middle of the night somewhere in Bavaria.
What must have concerned the U.S. military with regard to bin Laden was preventing the creation of a shrine to terrorists. When Deputy Führer Rudolf Hess was buried in Wunsiedel in 1987, neo-Nazis started to flock there to pay respects—that is, until the German government issued a ban any sort of rally taking place. Japanese war criminals were cremated, but their remains are interred at the Yasukuni Shrine, which has since become a source of controversy. Saddam Hussein, meanwhile, is buried in Tikrit next to his two sons—not that supporters have been flocking there. And then there's the odd case of Mussolini, who was buried intact until a Fascist sympathizer stole his corpse in 1946. It then went missing for several years (even stored in a steamer trunk) until a deal was made to return the body to the family crypt in 1957, with much fanfare from Fascist supporters. You can still visit that crypt today—it's in Predappio. You can even sign the guest book.
For more examples of how the bodies of controversial figures have been disposed of (such as the Ceausescus and even Oliver Cromwell), see my essay that appeared in Policy Review in 2005.