It looks like fans will have to wait until March 26th for any details surrounding Assassin's Creed III.
Ubisoft is holding a "special briefing" next week for Assassin's Creed III where they will reveal many of the game's details including the background, storyline, and the new hero who will replace Ezio. While it looks like press will have an early look at the game's details as early as next week, all reporting on the information is embargoed until the 26th.
As of right now, all we know about the new Assassin's III game is that it will be released later this year and feature a new hero who we know nothing about.
While that will definitely change at the press event, the franchises' official Facebook Page said today that a "major Assassin's Creed announcement is only days away."
More details about the upcoming announcement will be revealed tomorrow on the Assassin's Creed website, but I wouldn't expect too much more than a teaser.