The "why American Revolution?" crowd are overlooking something. The game series has never been about "assassins" but the secret war between the Order of Assassins and the Knights Templar. The period of the Revolution saw the founding of American chapters of the Freemasons (who have a connection with the Templar), and in fact George Washington was a member and was rumored to have been chosen as their leader before he was President. If that doesn't make an historical basis for an Assassin's Creed game I don't know what does.
Also, no idea if this has any significance or is just coincedental
Actually, looks like people already figured this out over a year ago