Launched last year with Assassin's Creed 2, Ubisoft's Uplay has served as an in-game rewards system on top of Xbox Live's Achievements and PlayStation Network's Trophies, letting those who sign up for it unlock bonus items using accrued points across supported games. Recently, these same folks got an email offering them a free bonus mission in Assassin's Creed: Brotherhood called "The Trajan Market." The mission was originally available as part of the game's "Codex Edition" and sends Ezio into a marketplace in the middle of Rome, where he fights Borgia guards and discovers a treasure hidden in a ruined tower.
As you can see in the screen grab above, the code was even sent out to Uplay members who don't own the game. If you're not yet a Uplay member, you can sign up on the official site. Also, you didn't tell us there'd be free stuff, Ubisoft! Oh wait, maybe you did.
Update: Ubisoft has clarified that this offer is for European Uplay members.