Seems there was a leak as to the setting of AC3, and confirmed!

The new AC will take place during the American Revolution. That’s a huge shift from the places it has been so far IMO, and I like it. I can only imagine what will happen and what side are you on. I am looking forward to it. I love the Assassins Creed Series. Its among my favorite series

http://kotaku.com/5889489/is-this-the-star-of-assassins-creed-iii