This DLC will hit in January with "Battle for Forli" and another one will follow in February called "Bonfire of the Vanities." There isn't much information about either of these DLCs - how much, where they fall in the story, etc. However, we do know each of these will be a whopping 1GB and you have to have the AC2 disc to play them (not too suprising).
My personal guess is that these might be the two "missing" DNA sequences that as Desmond you do not get to experience in the Animus. The story goes from DNA sequence 11 straight to 14, I wonder what 12 and 13 could be
Pretty much unless these are $20 each I am all over both of them. I loved AC2 and can't wait to see what they have in store for us.