Warner Interactive have announced their line up for Gamescom, and it includes two unannounced titles - one of which is a "major" announcement.
No information on what it could be, but if a sequel to Arkham City is planned for this generation it might be a good time to announce it.
As far as announced titles go Warner's line up includes Batman: Arkham City - Armored Edition, Injustice: Gods Among Us, Lego Lord of the Rings, Lord of the Rings Online and Guardians of Middle-Earth.