Assassin’s Creed: Revelations downloadable content will be included for those who pre-order certain special editions of the game.
It is a bit confusing, so to make it all a lot more simpler, pre-ordering ahead of the Assassin’s Creed Revelations release date on November 15, 2011 from GameStop will net you an additional downloadable content mission known as the Vlad the Impaler mission.
This single-player mission is set during a prison and the DLC will be free to download for those who pre-ordered the game. Pre-ordering at GameStop in America automatically upgrades your version to the “Signature Edition”.
If you live in Europe, either of the Assassin’s Creed: Revelations Collector’s Editions will net you the special DLC mission.
See the link for details on what else is included for each version in each territory, jotted down in a clear and easy to understand manner.
Here is a trailer for Revelations.