Another downloadable content pack has apparently been outed before its time. The Mediterranean Traveler Map Pack was spotted on a retailer product page, which also dropped a release date of January 24, 2012 and a (possibly tentative) price at $9.99.
The GameStop page (via Joystiq) is short on other details, but it all seems too specific to be a fluke. The Assassin's Creed Wiki claims the maps will include Siena, Jerusalem, Dyers, San Donato, Firenze and the Imperial District of Constantinople, but it states the price differently and is unsourced, so take it with a grain of salt.
When releasing DLC for Brotherhood, Ubisoft teased the second DLC pack when they released of the first one. If they repeat that strategy, we'll hear official details on the Mediterranean Traveler pack on December 13, when the company launches the Ancestors Character Pack.