An Assassin's Creed developer interview, and Easter Eggs from both Assassin's Creed and Watch Dogs, point to the games taking place in the same universe.
via N4G: pc news feed http://n4g.com/news/1385986/3-reasons-assassins-creed-and-watch-dogs-are-the-same-universe
via N4G: pc news feed http://n4g.com/news/1385986/3-reasons-assassins-creed-and-watch-dogs-are-the-same-universe