You can't end war on a word
As the Carpenters sang back in the day, "It's only just begun......."
no, it is definately not over. osama did a very good job spreading his beliefs over a vast amount of land and people. and if the united states government is refering to the war on terror as to abolish most or all terrorist groups in the middle east then the war will not be over in hundreds if not thousands of years.
Obviously there will be unhappy Osama-supporters after revenge. They will be one cause among many for a continued war.
As long as the true version of Islam is preached, Terrorism will never end