According to www.gamestop.com Assassin's Creed : Brotherhood will come to the PC platform in 2/22/2011
(February 22). It's even available to pre-order and you will get a bonus an exclusive multiplayer character.
More info at http://www.gamestop.com/Catalog/ProductDetails.aspx?product_id=77864 if the link doesn't work go to www.gamestop.com and search for Assassin's Creed : Brotherhood. PC fans get ready